Elspeth Bowman, an old lady who owns a local shop, asks Ken to keep an eye on her son, Cecil, who is about to be released from prison. Two friends of his, Mitchell and Kelloway, "from the Territorial Army", want to organise a welcome-home party for him at the Plaza Suite.

Cecil is a genial, long-haired, middle-aged man who suddenly has access to large amounts of money which he spends freely on new cars. Is it the proceeds of the robbery for which he was imprisoned. He never revealed the names of his accomplices but the police are almost certain that they are Mitchell and Kelloway. In fact Cecil's money is simply the result of a win on the premium bonds that he invested in a unit trust.

Cecil pretends to go along with a robbery that Mitchell and Kelloway tell him about during the party. They have already taken photographs of the outside of Stansfield Hall, a stately home, and Cecil goes on a guided tour of the inside during an open day, in order to memorise the location of any valuable antiques. In reality he is co-operating with the police so as to incriminate Mitchell and Kelloway in revenge for their letting him carry the can for the earlier robbery.

Rocky is feeling very depressed after he has been dumped by Anna McLeish, a girl that he has just met. He wants to be given more interesting and stimulating work by Ken and Margaret, so they set him a challenge to test his powers of observation: he must train himself to remember forty objects on a tray. After a lot of coaching from Margaret's daughter Jo, he eventually succeeds.

Harry has a problem with mice at the Plaza Suite: they are getting in the fridges and running across the floors. While the ballroom is closed for cleaning, Harry is approached by an effeminate white-suited man, rejoicing in the name Simon Dangerflower (!), who represents the Society of Beleagured Husbands. Amid strict secrecy he is laying out dominoes in the shape of the Society's logo. He plans to topple the dominoes in front of the TV cameras as a publicity stunt, but just as the cameramen are setting up their equipment, one of Harry's mice sets off all the dominoes prematurely.