Chickens, Roosting - S1.E18

Alastair and Nicky's relationship becomes frosty as well as his relationship with his father because of his adoption. Arthur is having trouble with his breathing and is admitted to hospital. Nicky and Cliff go to Kieran and Amanda's for dinner and are joined by Alastair. But it doesn't go well as Cliff finds out from Keiran that Nicky slept with Kieran before him and leaves the party. Amanda and Alastair have sex in the kitchens after the party breaks up as Kieran seeks out Nicky. William tells Louise the circumstances of Alastair's birth and adoption. Cliff shows up at Nicky's home later that night and she tells him she will never sleep with Kieran again which reassures Cliff.