The Annals of the Heechee is a science fiction novel by the American writer Frederik Pohl, published in 1987 by Ballantine Books. It is about a dead space explorer's machine-stored version who is trying to discover why the Assassins, a mysterious type of pure energy beings, are threatening the stability of the universe. It is part of Pohl's Heechee Saga, which is about the Heechee, a fictional alien race created by Pohl. The Heechee developed advanced technologies, including interstellar space travel, but then disappeared. Source: Wikipedia (en)