Henry Crabbe (Richard Griffiths) is posted to guard a jury deliberating in a fraud case, who have been sequestered in a ghastly hotel. Crabbe has to find out who is intimidating the jurors, and how the villain is getting to them. Meanwhile he comes to the aid of the hotel's talented cook (John Thomson) who is cruelly oppressed by the jobsworth manager. Back at Crabbe's restaurant an obnoxious customer is giving new waitress Sally (Marsha Thomason) a hard time.

Fisher sends Henry and the squad to a meat factory where animal rights protesters are demonstrating against the owner,Mr. Trubb's use of veal in his Trubbs' Thunderbolt sausages. However, Henry finds to his surprise that the sausages contain soya and are wholly meat-free. Margaret, meanwhile, is concerned when her friend Julia, a wealthy widow, falls for a pilot much younger than herself and agrees to finance a bucket shop for him.

Henry and his team are called to a private boarding school where police Commander Colin Stilwell's son Alex has been beaten up by local youths. Henry initially encounters a wall of insular hostility from the establishment before Alex points him to another pupil, who has blackmailed the Chemistry teacher into manufacturing Ecstasy tablets, which he is selling around the school. Gary meanwhile creates a new blend of mustard and attracts the attention of a large food manufacturer who offer to market it. However, they want to alter the recipe, making it taste more bland, whereupon Gary, taking a leaf from Henry's book, puts his culinary principles first and tells them that the deal is off.

Henry has to solve a series of thefts from lorries and gets unexpected help from private security firm Troubleshooters. Their accuracy is such that he is suspicious of how they came to know of the crimes and believes that there is a possible informer within police ranks feeding them information for a reward. Troubleshooters are due to play the police eleven in an important football match. Both teams boast an ex-professional, in the police team's case Kirk Flowerbridge, who has a murky past and a liking for the drink. Fisher tasks Henry with minding Kirk and keeping him sober for the match. In the process of helping Kirk,Henry gets to identify the informer.

The Crabbes holiday in London in a flat owned by ex-policeman Nick Spencer whilst he is in America on business. However Margaret finds his packed suitcase under the bed and hears an answer-machine message from his daughter warning that her violent ex-con boyfriend Danny is on his way to see him. Henry discovers Nick in hiding whilst Margaret discovers Danny's corpse in the dust-bin, killed in self-defence by Nick. Henry's loyalty is put to the test, as is the patience of Sally and Gary when the agency staff turn out to be a quarrelsome married couple.

As Henry mysteriously loses his sense of smell he is intrigued when Fisher seems obsessed with arresting tyre exporter Peter Watson and suspects that Fisher, about to divorce his wife, is having an affair with Mrs. Watson. In fact she has discovered that her husband is defrauding her charity and is using Fisher to trap him. Having seen the case through Henry, feeling used by Fisher to catch Watson, resigns from the police and immediately regains his sense of smell. With Gary turning down the offer of work at another kitchen, Henry and his staff and colleagues have every reason to drink to the continuing success of Pie in the Sky.