Max in the Capital of Spies

Max Fredericks can time travel. He doesn't know exactly how it works-just that it does. When it happens again, Max finds himself on the wrong side of the Iron Curtain in 1965 East Berlin. Still queasy from the shock of travel, he witnesses an abduction. The victim is a girl Max later comes to know only as Elsa, and the perpetrators are the Stasi-"the sword and shield of the state" in communist East Germany.
Armed with comprehensive knowledge of the Stasi only a nerd from the future could possess, and assuming the girl is a damsel in distress, Max decides he's the hero of this story and sets out to rescue her. But what he doesn't know can hurt him. The clock is ticking as Max works to outsmart the Stasi, dead-dropping and brush-passing, double-crossing and being double-crossed as he goes. Can Max infiltrate the Stasi HQ without getting himself locked up in a gulag or shot as a spy? Why was Elsa targeted? And how can Max get back across the Berlin Wall and home to the present?