The children won't sleep - Paul and Ally thought these nights were over. Paul spends the night fighting his own anger and his children's inability to go the f**k to sleep.
Luke's parents evening and the surprise arrival of Ally's estranged father cause Paul and Ally to examine their hopes and dreams for Luke and Ava and discover how far they are willing to go for the sake of their children.
Ally attempts to acclimatise to Michael's continued presence while Paul, suspected of intentionally hurting his mum, begins to question if his accident-prone son's frequent injuries might actually be his fault.
Michael thrives in his new role as dad and granddad, but Paul and Ally can't adapt to his presence as easily as the children can; Luke's hunt for proof that Santa doesn't exist puts Paul's claim that he never lies to the test.
Paul and Ally are thrilled that Sprout the family gerbil has finally died, but explaining loss to Luke and Ava is more difficult than they thought as grief manifests itself in mysterious ways and throws the family off course.
In the wake of Michael's death, the family stay with Darren (Patrick Baladi) at his country house, but Paul's attempt to give Ally space by taking on kid duties and Darren's fixation on work doesn't help Ally find a chance to say goodbye.
It's half term and Luke is responsible for taking Lenny the class bear on an adventure. Lenny has been to Italy, Peru and beyond, but Paul can't even manage to get the family and the godforsaken bear out of the house to the local park.
Paul attempts to focus on his upcoming wedding but is constantly thwarted by his family; Ally is distracted by work, Luke is misbehaving at school and Leah doesn't understand why they are even bothering to get married.
Family life is thrown off kilter as Ally spends her weekdays in Berlin and weekends in London. Paul, Luke and Ava try to muddle through without her, but the children aren't sleeping again and it takes its toll on Paul.
Luke's condition worsens and he is admitted to a specialist pediatric unit. As Paul, Ally and their parents desperately wait for news, stress and fear cause cracks to form within the family.