The murder of a man at an exclusive rehab clinic grows more intriguing when the centre's slippery founder is announced as beneficiary of the dead man's fortune, and the copper's job gets more complex as his new DS turns out to be an old flame.
The murder of ex-hippie Marion Dove leads the team to suspect members of her family, who hoped to inherit her successful glass factory. However, the reading of the will uncovers a new twist - the woman had a secret child, to whom she bequeathed everything.
The team visit a well-heeled suburban close where a man has been found dead in a back garden, though no-one on the street admits to knowing him. Meanwhile, Alex decides not to invite Mayo to her housewarming, angry at him for feigning indifference about the party.
With Alex jealous over Mayo's telephone conversations with a mystery woman, the team struggle to focus on the demise of an old man bludgeoned to death in his wheelchair. The victim seemed a harmless member of his local church, but the detectives soon learn he had plenty of enemies, not least in the residential care home he owned.
A salon owner's estranged husband is murdered, prompting Alex to go undercover for a makeover and to gain information - much to Mayo's amusement. The investigation struggles as there are no obvious suspects, while the neighbours of the house where the body was found all point the finger of blame at each other.
An investigation into a geography teacher's murder reveals he had a gambling problem. Suspecting the man's wife was dealing to pay off the debts, Mayo calls in the drug squad, and their detective Mike Dean is soon making himself useful - as well as impressing Alex with his good looks.
An estate agent is found murdered on the eve of his wedding in a property for sale with a rival agency. With the owner of the other firm missing the case seems straightforward, but the emergence of a possible motive for the dead man's fiance complicates matters. Elsewhere, Mayo angers daughter Julie by suggesting they put their house up for sale.
Alex is offered a promotion in London, and with Mayo refusing to admit his feelings for her, she decides to tell him she has accepted it. The pair work on what could be their last case together when a cleaner is asphyxiated with a duster, and the investigation leads them to a local politician whose house the murdered woman cleaned.