"Tiiii-na...good dog...Tiiii-na...come heeeerrre..." Edward and Gina Reynolds are an affluent but lonely middle class couple living in Chelsea. Devoted to each other, their other great joy is their white poodle Tina, whom they look upon almost as a child. But a series of unpleasant letters that begin to arrive on a daily basis threaten their cosy lifestyle, with the unknown sender accusing Mr Reynolds of being a "snob" with a "snob dog". Though distressed, they pass the letters off as the work of a crank until their beloved Tina vanishes in the park one night. After searching high and low, they soon discover her fate when another letter arrives and demands 200 pounds for the return of the dog. They acquiesce, and Edward Reynolds leaves the sum between the railings of a fence that evening. But the dog is not returned, and another letter arrives demanding still more money. Turning to the police, Mr Reynolds receives no joy when they fail to take the matter seriously. However a young, ambitious constable named Clarence Duhamel believes he can help the Reynolds and visits their flat with the intention of helping them in his own time. Sadly, unbeknownst to everyone, the dog is already dead - drowned at the hands of a Polish sociopath named Kowajinski. Using confidential information gleaned from his social worker girlfriend Marion, constable Duhamel or "Clarrie" as he is known stumbles across the dognapper and demands the return of the poodle to the Reynolds. However Clarrie does not reckon on the vindictive, bitter nature of Kowajinski, and quickly finds himself outwitted by the old man and accused of taking a bribe. Now under official investigation, Duhamel is pushed into a show of strength as he faces the ire of his police colleagues, who dislike him because of his Cambridge background. One detective in particular - Choley - despises Clarrie, whom he derogatively refers to as "Girlie". Clarrie turns to the Reynolds, whom he feels an affinity with and