Steve is looking forward to a relaxing (and perhaps romantic) time under the Spanish sun with his friend, Laia. But when an email from his brother DJ arrives, implicating their grandfather in shadowy international plots involving nuclear bombs, Steve and Laia put aside all thoughts of a lazy, sun-drenched vacation. In a desperate attempt to find out if Steve's grandfather was a Cold War-era spy, they crack mysterious codes, confront violent Russian mobsters, dodge spies, unearth a bomb and avoid nudists. But the more they uncover, the more Steve wonders: whose side was Grandpa really on?