Laura Poitras's Oscar-nominated documentary Citizenfour is proof that you can make an espionage thriller without car chases, bikini babes or martinis.

There's footage from within the Ecuadorian embassy in London as Julian Assange helps with the flight that takes Snowden to Moscow, where he claims political asylum. These scenes give the film an unprecedented level of immediacy and dramatic tension.

Poitras' movie works even better as a horror picture -- perfect for Halloween week.

This isn’t a film that pretends to an impossible objectivity: its powerful effect on us resides in the urgency with which it makes its case that global communities are at great risk from governments acting in the name of security.