Gravity's Rainbow is a 1973 novel by American writer Thomas Pynchon.
The narrative is set primarily in Europe at the end of World War II, and centers on the design, production and dispatch of V-2 rockets by the German military.
In particular, it features the quest undertaken by several characters to uncover the secret of a mysterious device named the "Schwarzgerät" ("black device"), slated to be installed in a rocket with the serial number "00000". (wiki)