What kicks off splendidly as a heartstopping, out-and-out chiller hangs a left into comedy territory only for it to swing back to full-on mindnumbing dread. And then back again.

The opening scene is the master firing on all cylinders. As a light breeze drifts through Central Park, breakfast walkers stop in their tracks. And then start killing themselves.

One never-shredding sequence shows construction workers serenely walking off scaffolding walkways to fall to their deaths below. Similarities to the World Trade Center "jumpers" are terrifyingly unavoidable. 

Across town, science teacher Elliot Moore (Wahlberg) gathers up his wife Alma (Deschanel) and they head off by rail together with his buddy Julian (Leguizamo) and his daughter.

However, after the train halts in a remote Pennsylvania backwater it becomes apparent that "the event" which struck New York is targeting even the smallest rural community.

There's a lot of promise here. Shyamalan admirably attempts to flesh out Elliot and Alma's troubled relationship...but this takes the form of a comedy routine which is a touch puzzling next to the grim scenes of roadsweepers hanging from trees or wannabe suicides opting for death-by-lawnmower.

So we're left with two movies in one: a gripping War of the Worlds-style psychological scenario and a lighter caper living within.

Use your (sixth) sense to figure it out.

Tim Evans