The plot, reminiscent of the Alfred Hitchcock film ''Strangers on a Train (film)'', focuses on two disparate characters. Conservative Henry Bell has been eased out of his job by condescending Bruce Tick, while wealthy and wildly eccentric Karen Knightly has been abandoned by her lover Anthony Staxton-Billing, who opted to return to his wife Imogen. Both are intent on committing suicide by leaping from the Tower Bridge in London. When neither succeeds, they strike a bargain whereby each agrees to exact revenge on behalf of the other, although Henry is less enthusiastic about the plan.