"The East," the new thriller from the duo of Brit Marling and Zal Batmanglij, starts with a creepy bang. Static-filled security camera and handheld footage shows crude oil oozing from the vents and openings of the opulent household of a wealthy oil baron.

Co-star Ellen Page threateningly drones over the whole affair, claiming the attack for The East – an intensely secretive and potentially dangerous crew of eco-terrorists – and ominously reciting their mission statement: It shouldn’t be easy to live with crimes against the environment and mankind. Poison us; we’ll poison you back.

It’s a creepy and intense opener that hooked me in quite nicely. Then again, Marling and Batmanglij have never had a problem with hooking in audiences; it’s the delivery that’s eluded them.

Marling’s big debut, the Sundance darling "Another Earth" that she starred in and co-wrote, rendered its fascinating dual-planet premise emotionally mute. Then her first feature film collaboration with writer-director Batmanglij, the cult thriller "Sound of My Voice," was all mystery with none of the pay-off (as well as a chapter structure that flowed into the film as well as a bullhorn in a funeral). The results are a bit more consistent this time around.

"The East" finds Marling and Batmanglij heading back to the infiltration themes of "Sound of My Voice," this time with dozy-voiced Marling playing the intruder rather the enigmatic leader. She’s Sarah Moss, an agent working for a private intelligence firm (run by the always reliable Patricia Clarkson) investigating the eco-terror cell.

A new hair color, a fake ID and some convenient connections later, she’s in the group, hiding out in their dingy, off-the-grid forest home. She meets their leader, the vaguely self-righteous messiah Benji (Alexander Skarsgard); their kind but shaky doctor (Toby Kebbell); and the cold, distrustful Izzy (Page). After some light hazing, Sarah is brought into the group just in time for their latest attack: infecting the CEOs of a major pharmaceutical company with their own destructive drug.

Marling and Batmanglij have a far stronger and more composed hold on their story in "The East." Gone are the cryptic clues for the sake of having cryptic clues. Instead, the mysterious elements are nicely woven in the film.

The result is a tense, crafty little spy thriller with their signature creepy notes interspersed throughout, such as a strange bonfire training sequence featuring The East operatives wearing eye-less paper masks of their CEO targets. An early dinner test for Sarah is also a half-fascinating, half-shiver-inducing look into the hive mind of the group.

Batmanglij, the directorial half of he and Marling’s collaboration, has a good eye for unsettling little details. He wrings a lot of tension out of the film’s brief, fleeting glimpses of menace, such as the junior anarchists’ nifty infiltration of the CEOs’ garden party.

Other times, it’s a graffiti message left by a deaf deserter, warning the group that "this house is not safe," or simply the way he frames shots – a lot of symmetry – in the dark, damp house. He creates a nice air of mystery and intensity that makes the group, and Sarah’s task, all the more riveting.

It all builds toward a moral dilemma: Is The East is right in punishing corporations for their consequence-free behavior? Should they go further or have they already gone too far? And is Sarah in too deep to know what the right answer is?

It’s an interesting situation, but old habits die hard for Marling and Batmanglij. After spending much of the film building up and cautiously immersing the audience into The East, the "in too deep" drama of the last third can’t quite sustain the intrigue.

Instead, it turns safe and standard, taking some predictable turns, adding in a steamy romance and draining the story of its ominous, eerie mystique. They’ve upgraded from the lack of resolution in "Sound of My Voice," but only up to half-hearted resolution.

Where the film ends turns out to be a lot less interesting than where it started. Even so, "The East" is still entertaining and a further, more confident step in the right direction for its creative duo. Marling and Batmanglij have always had good concepts. Now they’re even closer to turning them into good movies.