The laughs don't always come easy -- but, oh, they do come -- in Cyrus, a dark comedy that repeatedly dances so close to uncomfortable territory that viewers figure it's only a matter of time before it topples right over into the taboo.

John C. Reilly, often cast as amiable if off-putting losers, plays another one, but the twist is that here, his character ends up seeming well-adjusted when compared to the title player. Reilly's John, long divorced from a more sensible person (Catherine Keener) who nevertheless has remained his friend, is depressed by his unwanted solitude and reluctantly attends a party to meet people. He hits it off with the sweet Molly (Marisa Tomei), and it looks like the start of something special. But John soon comes to discover that Molly lives with her 21-year-old son Cyrus (Jonah Hill), and the dynamics between mother and son -- these two seem really close -- make John uneasy. But neither he nor Molly want to mess up a good thing, so they work on building a lasting union -- one that the dependent and jealous Cyrus will do anything to sabotage.

The vicious feud between John and Cyrus provides the movie with much of its black-hearted humor, and the suspense over the depths of the parent-child bond supplies the unease. Yet for all its edginess, this isn't a cruel comedy by any means. Instead, it's as much a sympathetic study of lonely souls striving to make (or keep) connections, and Tomei, Reilly and even the limited Hill (who's perfectly cast here) all deliver raw performances that help us understand their behavior. The biggest surprise regarding Cyrus, then, is that it's ultimately as sweet as it is sour.