On a new year road trip to compete for funding, Jac, Ric and Sacha confront some old enemies. Serena's worst fears are realised.
A face from the past continues to wreak havoc when he returns to Holby. Nicky and Cameron go head to head when Jac offers one of them an opportunity for promotion. And Serena shepherds her flock down on AAU, when an old associate arrives and upsets the status quo.
Dominic desperately tries to inveigle his way into working alongside new Consultant, Ange Goddard, only to find that she's not that impressed with him. Meanwhile, Cameron bites off more than he can chew when he clashes with Jac, and Ric's ex-wife returns as a locum for the day, much to his dismay.
Frieda is happy that her life is back on an even keel, but her contentment is shattered when ex-boyfriend Roman unexpectedly reappears. With their relationship going well, Zav is keen to step up and ease the burdens weighing on a stressed Donna. But all does not entirely go to plan when he embarks on some impromptu parenting of Mia. Ange feels the pressure as she works to sell her vision for her Young Adult Unit while treating a difficult and vulnerable patient.
Ric goes above and beyond to treat his patients when Holby is overwhelmed by a winter crisis, while a grief-stricken Frieda immerses herself completely in her work, causing concern for Jac and Fletch. Ange has her work cut out on YAU thanks to an obstinate teenager, with Essie persuading her to enlist help from an unlikely source.
Can Ange convince her patient to proceed with a life-saving operation? A resolute Ric campaigns for change. Does Nicky have the strength to fight for what she wants?
While Holly's condition weighs heavily on an emotionally invested Ange, Holly's distraught parents must put their differences aside to make a heart-breaking decision. When new locum Chloe covers on Darwin a smitten Cameron sets out to impress. And when a disgruntled Xavier is tasked with treating spiritual Carole, it's clear she's not the only one in pain.
Zosia returns to Holby looking for work, while a frustrated Jac tries to track down Frieda. Elsewhere, Ange admits there is no hope for her patient, Holly, while Donna and Xavier clash over their new living arrangements.
Zosia's big news gets a mixed response and her situation is further complicated when a colleague from the US turns up. Sacha is rattled when an old flame appears on the ward with their ill and suffering partner. Following an incident with protestors, Jason refuses to leave Hanssen's office until his demands are met.
After a computer virus shuts down the hospital's power, Jac and Connie fight to save the lives of close friends. As the hospital is evacuated, Ric mounts a desperate rescue for a trapped Essie. Meanwhile, Ange and Serena clash over Holly's care and continued life support.
A desperate Ange pleads with Holly's family to see reason, but when the ruling comes back, the anger finally boils over with devastating consequences for Fletch. Ric's son Kofi arrives at Holby wanting to find out what's going on with Darla. Struggling to keep his granddaughter's pregnancy a secret, Ric battles to keep his family together and do what's right for everyone. An excited Zosia looks forward to working with Frieda, only she doesn't get the reception she was expecting. As the pair team up to tackle a case, Zosia does her best to win over Frieda, with hilarious results.
Fletch worries there may be more to Theo's disappearance than meets the eye. Chloe's day is thrown off balance when a surprise visitor appears, and Donna meets Xavier's mother for the first time, but things don't go as smoothly as expected.
Ange follows a hunch and ends up uncovering a shocking and long-buried secret - one with the potential to completely tear her life apart. A downbeat Frieda faces tough choices when an old friend of Roman's appears in Holby in desperate need of help, while Cameron and Xavier are forced together on Darwin, where Xavier appears to take delight in Cameron's dating woes.
Chloe is wrong-footed when ex-boyfriend Evan unexpectedly turns up on Darwin. As Ange reels from her recent discovery, Dom is also confronted with life-changing revelations. And when Mia appears on the ward, Donna faces some tricky parenting dilemmas.
Dom throws himself into work as he struggles to process a shocking family secret. Zosia undermines Jac's authority and puts a strain on their already fraught relationship.
Zosia and Jac's relationship shows no sign of mending when Jac pulls rank over a patient's treatment. A startling incident then forces them to unite, putting everything into perspective and causing Zosia to reconsider her future at Holby. Cameron feels the pressure when tasked with treating Xavier's close relative, while an indifferent Dom tries to keep Carole at arm's length.
Jac's status is challenged when a dynamic and talented new surgeon Kian arrives at Holby and instantly causes a stir. Meanwhile, Dom is irritated when Carole starts work on reception, and Donna is flattered when a new career opportunity is presented.
Kian's big personality and alternative methods are beginning to grate on Jac, but is it just a case of professional jealousy? Fletch reminds her that she's only as good as her team and should allow him to thrive. Dom tells Ange he wants to be a proper part of her and Chloe's lives. In response Ange finally opens up to Dom, revealing a big family secret. When Sue makes a big mistake on her first day at the new job, Donna covers it up. However being the favourite of the new boss poses new challenges.
Ange plans to tell Chloe her biggest secret, when a surprise locum throws her day into disarray. Ric's granddaughter, Darla, arrives at Holby forcing him to deal with her pregnancy head on. Meanwhile, Kian rallies Nicky and Cameron to help him find out who Jac's mystery patient is.
Struggling from the news that Dominic is her half-brother, Chloe is forced to operate with him and Ange, but can they work through their personal pain? Lofty returns to Holby with a secret, but will his reunion with Dominic be a joyful one? And Sacha decides it's time to move back to his own home, but Jac isn't convinced he's ready.
Dominic faces his difficult past when he goes head to head with his abusive ex, Isaac, while Ange and Carole band together to try to help him.
As Dominic continues to treat Isaac's father, Lofty is determined to protect him, but when Dominic refuses to let him it puts their marriage in doubt and plays into Isaac's hands. A hungover Jac is mortified she can't remember how the previous night ended with Ken, much to Kian's amusement. She eventually gets her answer, but not before having to save Ken's life first.
In the hope of mending Isaac and his father Jon's relationship, Dom makes a risky decision which lands him in hot water. Hanssen finds himself in unfamiliar territory when an estranged relative arrives at Holby begging for his help. And keen for a new start, a revitalised Chloe throws herself into work when she returns.
Isaac continues to plot to drive a wedge between Lofty and Dom, but may have gone too far when he puts Lofty in harm's way. Cameron's good intentions backfire when an intervention ends badly, but he makes a selfless gesture when he is presented with an opportunity to protect Chloe. Hanssen tries to work out what is troubling an unusually quiet Oskar.
When Xavier's mum arrives on AAU talking in riddles, Donna does her best to shelter him from her behaviour - but will he appreciate the intervention? Sacha makes a romantic gesture but finds something unexpected in Patricia's cleaning cupboard. Nicky turns her nose up at working with Jac, who ensures she'll live to regret it.
Xavier tries to build bridges with Donna, but she's having none of it. Cameron can't quite shift his feelings of unease around Evan, and when he overhears a phone call his suspicions are confirmed. And Fletch is anxious about his first official date with Ange, especially when work threatens to get in the way.
Determined to put his troubles behind him, Cameron tries to prove himself to Kian, but when the pair clash over teaching methods, Evan steps in and manipulates the situation. Xavier is frustrated that Donna still isn't speaking to him, while Hanssen tries to get to the bottom of Carole's problems.
Chloe's day is thrown into chaos when Evan is attacked, and with his life on the line, he asks her a surprising question. Dominic is put under pressure when a surprise visitor arrives at Holby looking for Lofty. Wanting to keep his marriage intact, Dominic is forced to make a difficult decision. After a night of partying together, Serena and Fleur Fanshawe are thrown together to help a patient on AAU.
As her loved ones continue to worry about her, Chloe learns more about Evan. Cameron wants to get out from under Bernie's shadow, but he receives some devastating news. Hanssen learns that his grandson is not the only one who believes in the tooth fairy.
Kian struggles to cope with the anniversary of a family tragedy. The only way he can find hope is by vowing that he will save someone's life today. Hanssen fears his family history makes him unfit to raise Oskar, and questions whether nature or nurture will have a greater impact on the boy. Cameron turns down help from Alex as he tries to process a recent revelation, and Serena receives some surprising news.
The team gives a warm send-off to a beloved colleague, but a surprising revelation leaves Cameron reeling and he soon finds himself drunk and out of control on the wards. Under Lofty's guidance, Dominic takes steps to reconcile with Carole, only to end up making things even worse between them. Chloe is determined to sever all contact with Evan, but is forced to seek him out when he goes missing.
Jac is forced to make a career-changing decision when she is reunited with her daughter, who has been brought to the hospital by her ex's new fiancee. Cameron resists talking about his mother, while Serena's tough facade cracks as she seeks solace in an unlikely source. Dominic becomes convinced that something is going on between Carole and Hanssen, and his obsession brings him closer to learning the truth.
Chloe desperately tries to convince Evan that their marriage is over as he bombards her with calls, photos and flowers and refuses to take no for an answer. Hanssen is forced to choose between work and family as he prepares for an important operation, and Dominic and Lofty are surprised by the outcome of their relationship counselling, but secrets threaten to tear them apart.
A distressed stranger turns up looking for Raf di Lucca. Will her secret change Essie's life forever? Xav questions Ric's competence, but is Ric's outrage hiding a graver concern? Nicky learns to trust her instincts - and that includes suspicions about sinister Evan too.
Phoebe is admitted to hospital, and Evan accompanies her. Chloe is left dismayed by the development, as there seems to be no hope of cutting him out of her life altogether. Essie must make a difficult decision when a former patient asks her for a drastic favour, and Ric is concerned when a member of the Trust is admitted, and places the patient in Cameron's hands.
As the town is engulfed by a storm, Jac faces a devastating confrontation with her old rival Faye Byrne and the man whom they both loved. Sacha helps a grieving family that is torn over the issue of organ donation to come to a difficult decision. Patsy Kensit reprises her role as Faye for the first time since 2010.
Ric celebrates his 65th birthday, but as he continues to make mistakes at work, the return of a face from the past forces him to realise that his surgical skills are fading. Fletch risks his chances of making peace with Ange as he tries to discover if Chloe's story is true, and Essie is forced to assume the role of a newly adoptive mother after Sacha jumps to the wrong conclusion.