Game Without Rules is a short story collection by the British crime and spy writer Michael Gilbert featuring his counter-intelligence agents Calder and Behrens. The first US edition was published in 1967 by Harper & Row, and the UK edition in 1968 by Hodder & Stoughton. A second collection of stories followed in 1982 under the title Mr. Calder and Mr. Behrens. Source: Wikipedia (en)