Don starts to date a girl called Jenny, but her mood swings cause problems. When the couple join Sam and Brian's team at a local pub quiz in an attempt to beat arch-rival Derek things end up coming to a head.
Don manages to get himself and Jason a double date for him while conducting a tour of a new exhibition at a gallery. Don's girl Felicity ends up inviting them away for the weekend to her parents' country estate.
Don ends up surprising himself after he takes pity on pretty homeless woman called Susan. Sam ends up suggesting that he ask her out. When Sam returns home with Brian, she discovers Susan sitting on the sofa in their living room whilst Don runs her a bath. The following day Don doesn't want Susan to leave but after he offends her on a day out he tries to make it up to her by getting to know her friends better.
Don learns that Brian is going to ask Sam to marry him and realises that he still has feelings for Sam. Eddie suggests that Don sees a therapist where he ends up taking the therapist into his confidence and confessing his feelings for Sam, as well as some slightly shocking habits. Sam decides to throw a fancy dress party to celebrate Brian's birthday. Don feels unnerved when he learns that his therapist has come along in fancy dress. Don tries to find him at the party to stop him from revealing any of his secrets.
The Danbury household are preparing to celebrate Christmas and Don is making a final, desperate effort to lead a normal life. He has to deal with an out-of-control OAP though and a violent Santa.