Raf returns to Holby and desperately tries to get back to his former hard-working self, but he struggles in theatre, while Michael Spence creates waves with Guy by stirring up the pot.
Suffering from a crisis of confidence, Raf is pushed to the limit when he takes on a very complex specialist operation. Raf doesn't believe he's qualified, but Fletch and the rest of the AAU team agree that he is the best man for the job.
Mo fears she is being sidelined as Jac's career continues apace. Seeing an opportunity to prove her skills, Mo jumps at the chance to perform a groundbreaking procedure, but has she taken on more than she can handle?
As Zosia spirals out of control, Colette battles to save her from disaster. However, her efforts to protect Zosia bring her relationship with Guy to crisis point. Colette must choose between her heart and her head.
Fleur and Michael are pitted against each other in a race to diagnose a patient who is constantly arresting. When Fleur's ex-girlfriend arrives on Keller, it throws her off kilter. As the day goes on, it transpires that the two surgeons are not just in competition professionally, but personally too.
Adrienne expresses a morbid interest in ending her life and asks Serena to pull the plug. Serena refuses. But when Adrienne insists she doesn't want her life prolonged if her condition deteriorates, Serena faces a painful dilemma.
Guy collects Zosia from her clinic and allows her back into Holby, assuming that she's all better. However, as Zosia's behaviour deteriorates, can Guy see the truth of her situation before she puts herself or any patients in jeopardy? Meanwhile, a despondent Elliot fights for funding to enable him to build a prototype for his new device, but he finds Jac, Guy and the inescapable question of money standing in his way. Elsewhere, Raf pushes Serena to confront her feelings when she appears in work on the day of Adrienne's funeral, seemingly unaffected by the day's significance.
Jesse is forced to face up to how his dalliance with Zosia may have impacted her health. Zosia fights to prove to herself that her medication doesn't affect her abilities. Serena has to aggressively defend AAU from cuts imposed by the Holby board.
Raf is thrown when Amy has an unexpected request. With LA firmly in his sights, Dominic ruthlessly risks all to fulfil his ambitions. It's secret santa and as Mo plays detective, has she found her perfect man?
When a terminally ill patient claims that she recognises Zosia as her own daughter, Zosia embarks on a mission to save her life whilst trying to figure out their past connection. As the patient's condition rapidly deteriorates, Zosia's behaviour becomes worryingly out of control and Guy is pushed to take extreme action. Mo's elated when Jessie asks her to perform a duet with him at the Christmas party, setting her on a path to finally follow her heart and admit that she's fallen in love with him. However, this romantic notion is quashed when she spots Jesse kissing her sister Adele. Serena learns that Raf and Harry still don't know which of them fathered Amy's baby and she decides to lend a hand in getting the ball rolling. Amy confides in Serena that she wants to go ahead with the paternity test and Serena fast-tracks the results.
Elliot's preparing for a family ski trip when he is surprised by the unexpected arrival of an old friend. With his heart in the balance, Elliot must risk everything to save a life. Arthur proves wiser than his years when he comes to Zosia and Guy's aid as they struggle to deal with an uncertain future. A well-meaning Ric tries to give some fatherly advice to his AAU flock, but does he create more trouble than he calms? It's been a hard year for all and the AAU family must pull together to bring about some Christmas cheer.
Dominic is shocked to learn of wedding bells for Malick, and is tested emotionally and professionally when he gets stuck in the lift with a face from his past. Mo is determined to put on a brave face when she realises Adele is taking Jesse to a family wedding, and decides to find her own date. Realising there is no-one else quite like Mr T, she disappoints him by inviting him to the wedding as a friend.
Guy, after the arrival of a 'lost cause' on the ward and with the support of the Keller team, allows himself to come to terms with Zosia and her mental illness. It's the big day of the Effanga wedding, and a huge family secret is let slip.
Jac considers the possibility of a new start with Emma in the USA. Sacha's shocked when his daughter is admitted into Holby. Sparks fly between Harry and Mary-Claire. Was their New Year assignation really a one-off?
Fletch's ex-wife turns up on AAU, with dramatic consequences. Jonny goes head to head with Guy. A shocking discovery about Rachel knocks Sacha for six.
Sacha struggles to be a good father to Rachel in the face of a major revelation. Mo tries to hide from Adele, not ready to tell her about the family secret. Mary-Claire, desperate to deny her feelings for Harry, tries keeping him at arm's length.
An old friend gives Mary-Claire a fresh perspective on her relationship with Harry. Jonny tries to help a grieving mother do the right thing after the tragic death of her son. Sacha tries to bond with Rachel all over again, but the results are nothing short of disastrous.
Sacha is left reeling at the news that his daughter Rachel has left the hospital to meet her forbidden love. Harry realises that he has deep feelings for Mary-Claire. Mo is a step closer to unlocking the secret of who her real father is.
Is Sacha prepared to sacrifice the love of his daughter and do the right thing? Mary-Claire sets her sights on a career opportunity, but has a meddling Harry ruined her chances? Jonny believes that Guy is ready for a fall, but is he the man to bring him down?
When disaster strikes on Darwin, Elliot must choose between his team and his life's work - how will he decide? Mary-Claire's surprised by the return of an old flame. Is she ready to move on? Dominic and Arthur compete to impress, but are they stronger together than apart?
Harry takes the plunge and confronts his feelings for Mary-Claire head on. As Guy investigates the death of a patient, Jonny finds himself in hot water. When Zosia fears she is being sidelined, she takes matters into her own hands.
Harry wakes from his coma but faces a battle for his sight. Shockwaves ripple through Darwin when Jonny is arrested. Arthur frets over choosing a specialism but finds professional satisfaction in an unexpected place.
Jonny's finding life in prison hard going, but he doesn't stay locked up for long. Harry resists further treatment on his face until he's given a few home truths from a surprising source. Zosia, fed up with being treated with kid gloves, comes out fighting her corner.
Raf must overcome the doubts of his colleagues and his patient to perform Harry's surgery. Arthur tries to impress Serena to earn a rotation on AAU but finds the pace tough to handle. Mo has to make a choice about pursuing her father when she risks losing her last link to him.
Elliot and Mo fight to save Jonny from being returned to prison by a vindictive Guy. Harry presses a reluctant Raf for more surgery after the success of his first procedure. Arthur has one last shot to strut his stuff for Serena and win a place on AAU.
Jonny returns to work after his release from prison, with explosive consequences. Sacha is delighted to see Essie again after her time away in Germany, but realises that absence may not have made the heart grow fonder. Arthur suffers from first-day nerves on AAU.
As Guy struggles to hold it all together with the launch of the supercentre and Jac's disappearance, he's at serious risk of losing it all. An upbeat Mary-Claire prepares to face the future in Chicago without Harry, but when she makes a mistake with a patient, Serena suspects that all is not as it seems. Essie fights for her relationship with Sacha, but has he already moved on?
Fletch is horrified when Evie's first day at her new school leads to disaster. Guy is pleased to present his new hire on Keller, but he may be in danger of underestimating the lady. Adele decides to help Mo find her father.
Mo decides to arrange a meeting with her birth father under false pretences, but when Adele's suspicions are raised, will Mo be able to keep her secret to herself? Annabelle and Zosia go head to head with Guy over a special case, though Guy stands his ground. Is his future as secure as he thinks? Serena does her best to hold things together as the future CEO of Holby remains uncertain. However, she discovers an ally and admirer in an unexpected place.
Battle lines are drawn as new CEO Henrik Hanssen clashes with Guy. Oliver ruffles Jesse's feathers on his first day back at Holby and will have to earn his place on the Darwin team. Can a debt-ridden Fletch resist the temptation of a sure-fire racing tip?
Adele intervenes to bring Mo and her father together. Zosia offers to help Annabelle develop her groundbreaking experimental procedure. Raf sets out to impress Hanssen but, with a patient's pooch on the lose, his plans go awry.
Zosia steps out from behind her father's shadow and proves her worth as a surgeon. Raf must tread carefully when he offers medical help to a reluctant patient. Mo has mixed feelings when her estranged father Clifford starts working at the hospital.
The ghosts of Oliver's past threaten to derail his future. With his emotions in turmoil, is he fit to perform life-saving surgery? Raf finally unravels the mystery behind Lucy's injuries. Will he be able to protect her now that he knows the terrible truth? Essie freaks out when Sacha wants to take things to the next level. Is it too soon for such a big commitment?
Jesse and Adele have a rollercoaster ride of a day, which brings them closer together than ever. Fletch attempts to give his daughter the best birthday - in the face of having no money. Serena tackles the tricky subject of taking her and Angus's relationship to the next level.
A fiery Essie clashes with Sacha. She is determined to follow her instincts but is unprepared for the consequences. With increasing money pressures, Fletch crosses a line when he accepts an offer from a new 'best mate'. It's Adele's first day back, but who is Jesse trying to keep hidden from her?
It's Zosia's first day back on Darwin, but there's a fly in the ointment - Ollie. New AAU nurse Cara ruffles Raf's feathers when she intervenes and organises a psychiatric assessment for a patient. When Dominic is assigned to a neuro case, he finds himself holding the baby.
Guy and Jesse clash over Guy's surgical risk-taking. Sparks fly as duty psychiatrist Seb puts Zosia's head in a spin. Fletch is tempted by Clifford's 'victimless crime'
An exuberant new doctor on AAU puts Arthur to the test - will this prove a perfect pairing? Mo is back from Chicago, which sparks fierce competition between her dad and Mr T over how to celebrate her return. Dominic is shocked when a visitor from his past turns up at Holby with the sole intention of spending time with him.
Fletch finds himself at breaking point as his family are kicked out on the street.
Fletch finds he is in too deep with the pharmaceutical robbery.
Clifford's bad debts come back to haunt him when the gangsters turn unhappy, leaving Mo in terrible danger. On a busy AAU, Arthur's anxiety disorder takes hold, and he finds himself unable to cope. It leaves him so desperate that he starts to self-medicate. Sacha's left confused when Essie is off with him all day. After a few drinks she eventually blurts out the truth, confessing that she wants to have a baby.
A devastated Mo tries to keep her head above water while waiting for Adele to come round.
As Adele remains unconscious in ITU, an uncompromising Mo decides Fletch's fate, forcing him to finally confront his demons. Oliver worries about Zosia's blossoming relationship with Seb, leading him to overstep the mark, while Jesse throws himself into his work - but is he avoiding his true feelings for Adele?
Elliot faces a difficult dilemma when a woman from his past, Brigitte, arrives with a difficult medical case. As Elliot tries to find his balance in a tide of conflicting demands, he finds himself challenged anew by Brigitte - but is she the woman he remembers? Morven is delighted and intimidated when Serena takes an interest in her education. However, forced to stand on her own without Arthur, Morven finds her confidence wobbling - does she really have what it takes? Sacha gets up the courage to ask Essie about her plans for the future, but her answer comes as something as a surprise. Sacha must decide if he and Essie truly want the same things.
When Cara suspects that Raf may have developed a relationship with a patient, she must decide whether to betray her team or her principles. Dominic knows that Hanssen is far from impressed with him, but when an opportunity presents itself, can he show him that he's changed? Still reeling from the chaos his old friend Brigitte has brought to Holby, Elliot is thrown when he is offered a new job. Elliot must choose between his heart and head.
Guy's past revisits him when an old friend of his deceased wife is admitted to Holby. Troubled by his motives for treating this patient, Jesse implores Guy to reconsider surgical intervention. Will Guy gain the perspective he needs in order to leave the past where it belongs? Sacha is up against it on Keller, and it feels as though he is at odds both personally and professionally. However, wise words from an unlikely confidant help Sacha to make a very important decision. There is no denying that Oliver and Zosia share an attraction, and Seb, Zosia's psychiatrist boyfriend, is increasingly unnerved by their undeniable magnetism.
When Clifford is admitted after a road traffic collision, it becomes clear his illicit activities have escalated, putting not only himself but possibly Fletch and Mo in jeopardy. Ollie and Seb clash over a case, and though their disagreement seems professional, could Zosia be the real source of their conflict? When Jesse and Guy have differing approaches to a patient's treatment, it highlights the fault lines in their increasingly fractious relationship. Is their partnership strong enough to survive?
Guy is taken hostage and forced to hold a live grenade while the hospital is evacuated. The grieving husband of a deceased patient blames him for his wife's death and wants revenge. Will Fletch have to sacrifice himself to save Guy? Ollie and Zosia's feelings for each other are brought into sharp focus when they're placed in a life-or-death situation. Dom thinks he's being tested when Hanssen gives him a tricky patient to deal with - a man who is already suing his last doctor.
In the aftermath of the explosion on AAU, Arthur struggles to keep on top of his anxiety. He panics when Morven discovers he is self-medicating. Zosia's left reeling after the day's explosive events and her steamy kiss with Ollie. When Seb confesses his love for her, she's thrown into yet more turmoil. Sacha begins to question everything he knows about Essie when her old nursing friend turns up on Keller and reveals their wild past.
In the run-up to one of the most important days of Elliot's prestigious career, an unexpected case arrives on Darwin and forces Elliot to make some tough decisions. Should he take the path of least resistance or follow his heart?
Tasked with the mission of getting Arthur back on to the straight and narrow by a disapproving Hanssen, Dominic whisks Arthur away. However, in revisiting his past, Dom is forced to confront issues of his own. Can Arthur and Dominic both face up to their demons, and will their friendship survive?.