Trying to remember the name an Episode: a human soldier in a futuristic war is captured oleh a hostile alien race and he meets a human woman where he is being kept, etc

A soldiers in the future is captured oleh an alien species and he is put in a camera with another prisoner a woman who is slowly transforming into an alien (her skin is changing etc). At the end, he ends up telling this women what the aliens want to know from him (some military secret, like when they are attacking i think), but she turns out to an alien who is transforming back to her original form (not a human who is being transformed force-ably into an alien)...I am pretty sure it was a Twilight episode, but I may be wrong.