The Deep End nails its casting, and nowhere is that more evident than in its lingering shots of Tilda Swinton’s frozen face.

You get the sense that her Margaret Hall has spent years honing her composure. Before the film begins, that self-containment has “only” had to survive the loneliness of an often-unreachable husband and the constant peppering of questions and needs from her three children and live-in father-in-law. She holds herself together during the day and tries to reach out to her husband at night, to share the somewhat-fraught truth that their seventeen-year-old son, Beau (Jonathan Tucker), is mixed up with a Reno club owner named Darby (Josh Lucas). But she knows that the problems she sees–Darby’s age, his gleeful sleaze, his willingness to buy Beau drinks and then put him behind the wheel–won’t be what catches her husband’s attention. He’ll be too bothered by who Beau is to care about who Beau is with.

Then an accident leaves Darby dead beside the Halls’ dock. When Margaret finds him, her first instinct is to protect Beau, no matter what. She tries to erase any sign of her family’s involvement–but she soon finds out that Darby owed a lot of money to men now looking to collect his death from anyone they can strong-arm into paying it. And since they can send the police a sex tape featuring her son and the fresh “murder” victim, well, Margaret needs to find $50,000 fast.

It’s a solid setup, but what makes The Deep End really sing is the off-kilter and emotionally intense relationship Margaret develops with Alec (Goran Višnjić), her blackmailer. Alek puts pressure on Margaret, but he responds to her loneliness and vulnerability–first with a sense of honor and chivalry that he can’t quite shake and later with an aching adoration. Without even meaning to, Margaret turns him from extortionist to ally, forcing a confrontation between Alek and his brutal senior partner, Nagle (Raymond J. Barry), who is much more callous and much less inclined to call the whole thing off.

As I said, the casting is superb, as is the acting. Višnjić and Swinton have incredible chemistry–it’s hard to beat the poignant eroticism in a scene where Margaret has to lean over Alek and their lips almost brush–and Višnjić’s eyes mean he can pine at an Olympic level. Barry is exactly who you want as a hard-edged, reptilian late-game antagonist, effortlessly projecting that he lacks all of his partner’s more human qualities. Tucker knocks it out of the park as a kid just edging into adulthood and a world of complexities and responsibilities. And, of course, Swinton is riveting, with Margaret’s fraying calm and crumbling walls revealing her strength and her unaddressed need all at once. She’s in a world with a thousand demands on her time–poor woman can’t even hide a body without getting bugged about a missing baseball mitt or where she went on her walk–but there’s still something alien and ethereal about her (the Swinton specialty), which makes Alek’s response to her seem almost inevitable. There are some plotting weaknesses–it takes the upper-upper-middle-class Margaret so long to think of pawning anything that it may actually be intentionally funny–but the draw here is the characters, the emotional intensity, the mood, and the sense of doom and panic just beneath seemingly still and glassy waters. Highly recommended, and I’d add that the ’40s novel this is (loosely) based on, Elisabeth Sanxay Holding’s The Blank Wall, is very good as well.

The Deep End is streaming on the Criterion Channel.