Mercy Falls makes basic errors of dramatic orientation: mistaking characters’ bedhopping designs for personality traits, letting them act irrationally in service of the plot.

A wholesale suspension of disbelief is required to overcome the lapses in logic, but the edgy battle of wits that develops raises this above more derivative horror fare.

As it is, Mercy Falls has enough tension, emotional turmoil and blood spatter to make it worth a troubled trip to the wild woods.

The film is oddly watchable, maybe because its real star is John Rhodes’s cinematography of the Scottish highlands, a glorious patchwork of light and mist and trees and crags and glens on the way to the eponymous waterfall.