It's five years since we last saw the Worsleys, with Paul and Ally on the verge of splitting, and Jim and Jackie in turmoil. Things are no less dramatic now as Luke and girlfriend Maya drop a bombshell at Christmas dinner that will change everyone's lives forever.
The reality of Luke's announcement hits, and Paul and Ally worry about the decision he and Maya have made and whether they should support them. As a New Year starts, the Worsley family gather together with Maya's family, united in their love and worry.
Ally is appalled that she's about to turn 50 and bans the family from ever mentioning that number. Paul tries to help Luke, who is overwhelmed by learning to drive and becoming a dad, while Ava meets a charismatic girl called Holly.
A calendar mix-up turns Paul and Ally's fun night out into a stressful night in. A happy Ava finds her mood changing as the evening progresses. Luke turns up with an unwelcome friend and Carl finally sees the inside of the Worsley's house.
Paul and Ally find themselves parenting Jim and Jackie as well as a conflicted Luke. Ava and Holly get closer and Ava decides to take a risk, while Paul meets an old friend and realizes that he might, after all, be happy.
A chat with Darren and a chance encounter convince Ally she needs more friends, so she decides to reunite her antenatal class. Ally tells Luke and Ava this was a friendship group with no arseholes. But 17 years is a long time.
Paul and Ally are disappointed that their planned family holiday has become just the two them. But they soon make new friends. Luke is preparing for his new life with Maya and makes a massive decision. What follows leaves them both terrified.
Paul and Ally rush to fly back from their holiday when they hear that Maya is giving birth five weeks early. Ava and Sunil try to help Luke step up and become a father, but everyone is in shock when complications set in.
As Paul and Ally try to help Luke, struggling with being both a dad and a student, they find they have very different ideas about the best way forward. Jackie's condition is becoming more noticeable, and Jim is determined to help out.
Jackie's health is continuing to worsen. Paul helps out a distressed Luke but finds himself in more conflict with Ally. At Baby Jay's naming party, Ava declares her love, and Paul makes an offer that will take him and Ally back in time.