In the cool of April 1936, scientists Daniel Adams and Charles Chamberlane receive a mysterious package that includes a key and a map of the Belgian Congo. The directions say more packages are to be found, and the end result will be Adams's destiny. The note is signed "The Future." Suffering from unrequited love, Adams accepts the challenge and Chamberlane follows. They travel the world collecting pieces of advanced technology that only once completed and assembled will reveal their true function. Adams and Chamberlane encounter two mysterious men both named Mark-one is trying to stop them at any cost, while the other seemingly tries to help. Adams travels through time-1566, 1938, 2286, 1937, 2517, 1880, and finally back to 2481. Along the way, he encounters a mysterious woman who seems to know both him and the identity of his benefactor and his true motivations. Adams ponders the identity of the mysterious woman and wonders if and when she will reveal all she knows.