Harley Quin is a fictional character created by Agatha Christie and the most mysterious of all her detectives. His name is a word play on "Harlequin" which may be a clue to his personality. Mr. Quin helps his older friend Mr. Satterthwaite to solve crimes using his extraordinary skills and instincts. He appears in the short stories collection The Mysterious Mr Quin first published in 1930. Two short stories The Love Detectives and The Harlequin Tea Set (from Problem at Pollensa Bay and Other Stories) also feature Mr. Quin.