A serial in six episodes written for television by Edward Boyd from a synopsis by Len Fincham and Laurie Wyman.
[Starring] Geraldine McEwan and Jack Watling with Dennis Price and Sonia Dresdel

Ken Martin, well-known radio personality, and his wife, Kay, are told by a neighbour-Mrs. Curzon-that her flat has been burgled. The Martins go to investigate, leaving Mrs. Curzon alone in their sitting-room where she hides some diamonds In Mrs. Curzon's flat.
Kay and Kenneth find a cigarette case with the monogram 'C.D'. On returning home they discover that Mrs. Curzon has been strangled; later her body disappears and Ken is coshed while trying to get into her fiat to find a clue to the mystery.
They decide that the criminal must be Cecil Davenport-a poet who lives opposite-and they follow him to a club. On returning home they find that their flat has been ransacked. The following morning they receive a sinister anonymous phone call and are instructed to leave 'the property in their possession' in a specified telephone box. They mistakenly leave the cigarette case instead of the diamonds. They return home and Kay confesses that she still has the original monogrammed case, having substituted another one for it. Another neighbour-Charles Dingle-arrives and returns the package containing this second case which he says he found at the reception desk downstairs addressed to them.