The Ace of Knaves is a collection of three mystery novellas by Leslie Charteris, first published in the United Kingdom in 1937 by Hodder and Stoughton, and in the United States by The Crime Club. This book continues the adventures of Charteris' creation, Simon Templar, alias The Saint. Later editions of the book were retitled The Saint in Action. The adventures in this book mark the return of Templar's longtime girlfriend and partner Patricia Holm and his nemesis, Chief Inspector Claud Eustace Teal since The Saint Goes On.