DI Purbright and DS Love are convinced that they may be dealing with a man who is preying on middle-aged women and decide to focus on matrimonial agencies to see what might turn up. Sure enough, they soon discover that both of the missing women had registered with the same agency and were possibly exchanging correspondence with someone. They visit the local agency acquiring the name of a recently joined member, Miss Teatime but she rebuffs them insisting that she can take care of herself. When she's contacted by Mr. Trelawny, it soon becomes apparent that she is quite capable of doing so and she's even prepared for Mr. Trelawny's accomplice. (thetvdb.com)