It's no definitive masterpiece but it's damn close.

A lot of perfectly good film show their cards early, establish a unique premise and let the audience explore a topic at a leisurely pace, without much in terms of surprise. this film is not one of those films.

A film with more than the usual spoiler issues. Talking about it in any detail feels akin to handing you a gift-wrapped present and saying, "I hope you like it -- It's a thriller about a diabolical secret experiment."

Each character in this movie — down to the smallest one — is an individual rather than a type, prone to spontaneous changes of mood and sometimes amusing outbursts of pettiness or ill humor.