While visiting Colonel Melrose, Mr Satterthwaite hears of the murder of Sir James Dwighton, who had recently been in a messy love triangle and the wife and her lover are immediately suspected. But a chance meeting with Mr Quin, changes Satterthwaite's perception of the facts.

Whilst holidaying in the principality, Mr. Satterthwaite watches as a young American man falls in love with a mystifying Countess. Soon after a bit of gambling at which he was not successful, he bumps into Harley Quin and they invite their new friends for an intimate dinner that reveals dark secrets about one of the guest.

Mr Satterthwaite has come to Corsica with his friend the Duchess of Leith, where they meet the Duchess’s cousin Naomi Carlton-Smith. Distraught that her fiancé has been accused of stealing, Naomi turns to Sattherthwaite and his friend the mysterious Mr Quin for help.

Mr Satterthwaite investigates his friend's daughter, who appears to be hearing voices. Is it her imagination or is the sinister demand for something stolen a warning? Mr Quin glides into the picture, dropping clues and setting Satterthwaite's thoughts along the right path, as always leading him towards a resolution. In this story they again stay at 'The Bells and Motley', mentioned in an earlier short story of the same name.

After a performance of Cavalleria Rusticana and Pagliacci, Mr Quin and Mr Satterthwaite witness a fight outside the opera house – but what could have prompted such brutal behaviour? Mr Quin's appearance in the opera's interval suggest that forces of love and jealousy must be at work and someone is in danger.

While visiting the rather dull, conventional, country home of John and Anna Denman, Mr. Satterthwaite unexpectedly meets Mr. Quin on a narrow road called Harlequin's Lane behind the house. Locally, it's known as Lover's Lane. While exploring the lane, Satterthwaite meets Molly Stanwell and learns that there's to be an entertainment, a masquerade, that evening.

When Mr. Satterthwaite visits a new exhibit in London at the Harchester Galleries, he discovers a painting with a male figure that bares an unusual likeness to a mysterious acquaintance of his, Mr. Quin. With one bold move, he purchases the canvas on the spot and in another, invites the artist of ‘The Dead Harlequin’ to dine with him that night.

Mr. Satterthwaite has left the French Mediterranean for one of the Spanish islands. He encounters Anthony Cosden as he is about to leap to his death. This was not his first attempt at suicide. Can Mr. Satterthwaite and Mr. Quin bring happiness back to a poor man’s life?

Mr Satterthwaite much prefers to be in London and dislikes the country. Hence he turns down a dinner invitation by Madge Keeley to her country house at Laidell. However a message from Harley Quin sends him hurrying there.

George Dundas is sacked from his job for being a wastrel but he soon receives a golden opportunity. Will he waste it or grasp it?