Parker Pyne Investigates is a short story collection written by Agatha Christie and first published in the UK by William Collins and Sons in November 1934. Along with The Listerdale Mystery, this collection did not appear under the usual imprint of the Collins Crime Club but instead appeared as part of the Collins Mystery series. It appeared in the US later in the same year published by Dodd, Mead and Company under the title Mr. Parker Pyne, Detective . The UK edition retailed at seven shillings and sixpence (7/6) and the US edition at $2.00. The collection comprises twelve of her fourteen stories featuring detective Christopher Parker Pyne; the two remaining stories, Problem at Pollensa Bay and The Regatta Mystery were later collected in The Regatta Mystery in 1939 in the US and in Problem at Pollensa Bay in the UK in 1991 although these were originally stories featuring Hercule Poirot when they were first published in the Strand Magazine in 1935 and 1936 respectively. The book also features the first appearance of the characters of Ariadne Oliver, and Miss Felicity Lemon, both of whom would go on to have working relationships with Hercule Poirot in later books.