Director and co-writer Zal Batmanglij and his star and co-writer Brit Marling seem to have a thing for cults. Certainly their audience is in danger of joining a cult – of admiration for these two talented individuals’ work. In Batmanglij’s Sundance screened debut film, the startling, frightening, and provocative Sound of My Voice, the cult was a metaphor for faith, religion, fear, and belonging.

In The East, the tale of an undercover operative infiltrating an eco-terrorism cult – who may just have the right idea about life on this planet – is less metaphoric and more practical.

Part thriller, part think piece on the ecology of our times, The East features the compelling Marling as Sarah, ex-FBI, and current operative at a private firm providing damage control services for large corporations. Assigned to infiltrate and bring down an eco-terrorist organization called The East,  the audience is on pins and needles as she gains the group’s trust,  and begins to lose the trust and connection with her real life and boyfriend. In the process, she grows close to group leader Benji (Alexander Skarsgård), and the acerbic Izzy (Ellen Page).

Should the group’s bizarre doings in a half-burned down house be embraced, considering their corporate enemies are doing very bad things to the public at large? Or should the group be condemned for its vicious tactics, and devil take the hindmost approach to the protest game?

The film dodges these questions, and therein lies the problem that separates this thoroughly absorbing thriller from a run at greatness. Sarah’s thoughts and feelings are explored only superficially, and her surprise at the truly dark side of the corporate troubleshooting company she works for seems a bit far fetched.

Is the film still exciting, startling, and terrifying by turns? Yes.  Still, as an early viewer absolutely in love with Sound of My Voice,  The East‘s slicker suspense leaves me wanting more. Go see it? Absolutely. But check out Voice on Netflix or Redbox, for a full look at what Marling and Batmanglij are capable of achieving.

The East opens in theaters May 31st.