Five years after the events of season three, Paul (Martin Freeman) and Ally (Daisy Haggard) face their biggest parenting challenge yet. 18-year-old Luke (Oscar Kennedy) drops a bombshell over Christmas dinner that will change everyone’s lives forever. No longer in Luke’s shadow, 16-year-old Ava (Zoë Athena) experiences her own explosive moment when she meets the charismatic Holly (Jessie Williams) and instantly falls in love with her. Paul and Ally try, fail, and try again as they face these latest parenting challenges.