A psychiatrist friend of Ironside's is murdered, and the only clues are his collection of artworks. Is one of the artists the murderer? And if so, which one?

Driving to the garage whilst tired, Mark knocks down an old lady, with whom he develops a close relationship. It soon seems, however, that his guilt over the affair is going to lead to some revelations about his new friend that he might rather not hear.

A lawyer turns up at Ironside's door late at night, badly bruised and unable to remember what has happened to him. All that he can recall is that a man who needs rescuing is trapped in a sinking boat; but he cannot remember where the boat is, or who the man might be. The Chief begins a race against time to find the victim before it is too late.