Not since No Country for Old Men have I watched a movie that uses silence so effectively in the service of suspense. Drive comes close, with Gosling and Mulligan using silence superbly, albeit more to express mutual feelings than to inflate tension; the silence in Crawl however, is all about tension, tension in a near-Hitchcockian kind of way that recalls the classic age of suspense. The excellent score adds nicely to this suspense, jarring and deep when required, staccato and twitchy elsewhere, it provides nice color and taste to the proceedings.
