When Angus Monroe, a respectable Scottish lawyer, goes to Portugal for his annual visit to an old friend, he never expects to be involved in a murder, especially when he finds out that he is a major suspect. After he hears that the police are planning his arrest, Angus unwisely decides to flee the country. His escape is prevented when he realises that he has run into a trap at the border, where he narrowly escapes the police net. He heads for the one place where he thinks he will be safe—a ruined house near the scene of the crime. There, he runs afoul of those who are really responsible for the murder.
Back in Scotland, Mr. Jeremy Bottle, senior clerk of the firm where Angus is a partner, reads an account of the murder in the local newspaper and is shocked to find that the reputation of the firm may be in jeopardy due to the scandal. He decides that, even though he has never been abroad before, it is his duty to investigate the situation on the spot, conscious of the fact that he may not be in time to help in finding Angus.
