Triangle is director Christopher Smith's attempt to create a less-disorienting version of a Memento-like circular plot. Smith hit maturity with this film, which exhibits an intelligence and mastery of the craft not seen in his earlier Creep and Severance. The movie is unexpected and original, two words that don't get used enough.
Writing about Triangle requires trying to discuss the movie without revealing its surprising plot twist, so this will be a rather short review. Other films may get a spolier-warned discussion of their finer points, but there's no sense in doing that with this movie: the fun is all in following through its mind-bending twists and turns. Triangle was written over a period of two years after the completion of Severance and is based on an idea that had been bouncing around since 2004. Australian actress Melissa George was cast based on her performance in the HBO series In Treatment, where she played a therapy patient. The film is set in Florida but was filmed using Australian actors and locations by Mel Gibson's Icon Productions. Australian accents occasionally reveal themselves, but the cast overall is very good. George is excellent, which is a good thing because she dominates the screen time.
The mysterious opening scene shows a bitterly crying Jess, who holds her curiously inert son and tells him that "It's a bad dream...when I have a bad dream I close my eyes and think of something nice...like being here with you." She then arrives at a sailboat trip shaken by something of which she is unwilling or unable to speak. The boat's other passengers, who mostly are snobbish and insensitive, are no encouragement. A monstrous storm capsizes the ship, and its passengers find refuge on a passing ocean liner. The ship proves to be deserted, although there are disturbing indications that it is inhabited by someone hostile. That setup will be familiar to fans of slasher movies, but the film plays out in a psychological manner like some kind of slasher from a bizarre, alternate dimension.
This is far from a one-trick film that relies on a gimmicky, surprise plot twist. Triangle deepens with repeated viewings. It ends where it begins, and the ending gives additional information about its backstory that casts all of the previously seen events in a different light. The circular nature of the film's plot is foreshadowed in myriad ways: Jess says "every day is the same," then experiences déjà vu at every turn. It never becomes clear to what extent the events are imaginary or are really taking place. There may be no clear answers in this Moebius strip of a movie, but the questions are a lot of fun.