CINEMAX will air a documentary investigating whether Adolf Hitler was gay.

“The Hidden Fuhrer: Debating the Enigma of Hitler’s Sexuality” will air Tuesday, April 20 – Hitler’s birthday. It’s based on Lothar Machtan’s best-seller, “The Hidden Hitler,” and is produced by Fenton Bailey and Randy Barbato (“Monica in Black and White,” “Party Monster”).

Interviews in the documentary include gay Holocaust survivor Paul von Grozsheim, former SS officer Rocas Meich and a Bremen University sociology professor.