The three couples are returning from the Christmas markets in Cologne, but at the Channel Tunnel incorrect tickets, a looming strike and rude novelty Santas all spell disaster.
Trevor and Carol organise a camping trip for the group of friends but are also rekindling the fire in their relationship. Sadly, the rest of the group are less enthusiastic. The boys get into trouble while on a bike ride.
The gang are invited to a housewarming party for new neighbours Matt and Seb. Alan spots one of Joyce's old bedside tables in their house and thinks they have stolen it, so he hatches a plan to steal it back.
The couples attend the naming ceremony of Alan and Joyce's first granddaughter. John and Maureen are keen to get to know two well-connected party guests but they are more interested in Carol's erotic novel idea.
Mick returns from Spain without his young Russian wife Elena and soon causes chaos at the fete arranged by Carol. Meanwhile, John looks to spice up his and Maureen's relationship.
John celebrates his birthday at a murder mystery evening with the couples all in fancy dress. However, a real-life mystery emerges - is it Maureen or her character, Lady Greystoke, who is having an affair?
Maureen's mother, Joan, stuns everyone by announcing that she is going to marry a man 20 years her younger. The couples gather at the grand hotel for the ceremony and try to suss out Joan's groom, Roy.