After a mother and son are found dead, Taggart hunts after a murderer who's putting rat poison into food products made by a company called "Wonderland".
The investigation focuses on the shop from which the victims bought their food run by a married couple. Meanwhile, a mother-son pair of scam antique dealers seem to be having an Oedipal relationship while targeting an old woman.
Taggart and Jardine investigate a brutal dismemberment of a local loan shark. After his main competitor is killed by a car bomb in broad daylight, they begin suspecting a vigilante is targeting Glaswegian moneylenders.
Taggart's daughter returns home with news of her engagement, Jardine falls for an actress with a mysterious past, and a local moneylender fights for custody of his son. Then the killer strikes again.
Taggart discovers that his daughter's fiance spent time in prison for armed robbery, Jardine's actress worked at a gentlemen's club, and the two Edinburgh cops following the case from afar might not be as pure as the driven snow.
Taggart and Jardine go to Munich in order to prove that a man they suspect of murdering his wife is having an affair with her daughter. In order to placate his wife, Taggart brings her along as well but doesn't tell her he's on the job.
