Suzanne Lloyd was gorgeous as Diane, an ex model who at first seems to know more than anyone. At work Jack seems to be fighting an up hill battle as an executive of a company whose general manager (Finlay Currie) is described as "the last of the Victorians". Jack wants to bring things into the 20th century by liquidation the magazine department as it's losing money - he's also disappointed that during a heated meeting he doesn't get the support of his work friend.
Adding to the confusion Heath gets a call later that night telling him Diane's uncle has been killed but when he rushes over there it is to find him very much alive. Of course that is the only way to put him in the place when the real murder happens later on that night. And here comes Bernard Lee as Chief Constable Meredith who after a heart to heart with Diane realises her actions are those of a scared black mail victim. In the meantime
- who is Maddox and who is that mysterious man trailing her at the zoo -