Rob heads out to work unaware he’s forgotten he and Karen’s wedding anniversary. His mind ends up firmly on the job when he’s called to a drugs bust on the flat of Jason Merrick. The raid is ruined when an elderly couple, Bill and Mavis Bateson, inadvertently alert Jason to the police presence and, when no drugs are found, Rob is left looking after Bill and Mavis.
Later, Rob’s suspicions are aroused when a confused Mavis reveals that Bill is with their ‘grandson’ Jason, who they were visiting earlier that morning. Certain there’s a connection between the Batesons and the drugs raid, Rob follows Mavis to a warehouse where, upon seeing Rob, Jason flees as Bill lay unconscious on the floor.
In hospital, it’s revealed that Bill was carrying heroin in condoms in his stomach for Jason, who had promised the couple an end to their money worries. Rob gets a result when he convinces Bill to make a statement – but Rob’s boss is unimpressed.
Later, Karen rages at Rob for forgetting their anniversary but, as the pair kiss and make up, they are interrupted by a surprise party thrown by Cherry and Simon to celebrate 20 years of marriage.