Makepeace has been asked by her best friend, Sarah Hackett, to be the matron of honour at Sarah's wedding. Makepeace accepts. Makepeace is giving Sarah a lift to the railway station. Sarah is off to Harrod's with her father, Sir Lionel Hackett, who turns out to be a judge. Sarah is murdered while she is on the train. Makepeace is devestated when she is informed.

Sir Lionel, however, takes the law into his own hands. Makepeace gives Sir Lionel a photo-fit of a man who was seen at the railway station where Makepeace had taken Sarah. Sir Lionel assumed that he was the killer and goes in search of him. But, what Sir Lionel doesn't know is that he is looking for the wrong man.