In the face of an historical evil, would YOU have the courage to resist? It's a question that weighed heavily on the members of the CASSIA spy ring - a civilian resistance operation based out of a church in occupied Vienna. Vanessa Kirby joins ex-CIA officer Christopher Turner and Austrian intelligence expert Siegfried Bier to uncover a story of extreme courage in the face of insurmountable odds. In Part 1, we meet clergyman Heinrich Maier and rubber tycoon Franz Messner - unlikely friends who became the core of a new movement. Together, they recruited like-minded individuals to strike back at the Nazi regime. From SPYSCAPE, the home of secrets. A Cup And Nuzzle production. Series producers: Gemma Newby, Joe Foley. Produced by Morgan Childs. Music by Nick Ryan.