When actress Sarah Marshall dumps aspiring musician Peter Bretter for rock star Aldous Snow, Peter's world comes crashing down. His best friend Brian suggests that Peter should get away from everything and to fly off to Hawaii to escape all his problems. After arriving in Hawaii and meeting the beautiful receptionist Rachel Jansen, Peter is shocked to see not only Aldous in Hawaii, but also Sarah.
Emmy Coer, a computer genius, devises a method of communicating with the past by tapping into undying information waves. She manages to reach the world of Ada Lovelace, founder of the idea of a computer language and proponent of the possibilities of the "difference engine." Ada's ideas were stifled and unfulfilled because of the reality of life as a woman in the nineteenth century. Emmy has a plan to defeat death and the past using her own DNA as a communicative agent to the past, bringing Ada to the present. But what are the possible ramifications?