A good trailer doesn’t give away too much, but it also gives you just enough. You could be forgiven wondering just what “Aloft” was going to be about after watching the trailer; but still wondering what the heck it’s about after watching the movie is not so easily forgiven. This one takes some dedication to sit through.

Written and directed by Peruvian director Claudia Llosa (“The Milk of Sorrow”), “Aloft” seems straightforward enough: Jennifer Connelly plays Nana who eventually comes face-to-face with Ivan, a son she basically abandoned 20 years ago. A young Ivan is well played by Zen McGrath, but an intense Cillian Murphy plays this older Ivan; you’ll see them both as the movie haphazardly vaults between time periods, showing us a turbulent past and an odd present. Nana was a tough-as-nails veterinarian who eventually became some kind of new-age faith healer hippie. It was via this journey that she ultimately became estranged from her son. For some reason, journalist Jannia Ressmore (Mélanie Laurent), arranges their reunion, and much melodrama ensues.

“Aloft” is true to its title, filled with wafting bits of ephemeral imagery coupled with endless static shots of a brooding Connelly staring off into the ether. Actually her, and the other actors’ performances are powerful, but they’re not given much more to do than just look disturbed most of the time. Their characters are largely difficult to know and harder still to like, while the movie surrounding them seems to be trying too hard to be about something, but it’s not sure about what.

A good two thirds of the movie ticks by before things solidify enough to even follow. Incoherent as a whole, parts of “Aloft” are poetry, a rummage into the complexity of human relationships. But the time-shifting storytelling structure doesn’t do the movie and favors; unlike “Momento,” whose nonlinear storytelling made sense, there doesn’t seem to be a major motivation for the fragmented structure. “Aloft” seems just that — divided and adrift, with no solid motive for almost any of its developments.

Although the vague trailer may have seemed like it didn’t sell the movie enough, it may have actually revealed too much. Ultimately, “Aloft” is as well acted and wonderfully shot as it is maddeningly ambiguous and largely tedious. It’s a demanding watch about peculiar people.

REVIEW

• THE FILM: `Aloft'
• CRITIC RATING: *1/2
• STARRING: Jennifer Connelly, Cillian Murphy, Mélanie Laurent.
• PLAYING: Broadway Theater in Salt Lake City.
• MPAA RATING: Rated R for language and some sexuality. 112 minutes.