Soccer mom Margaret Hall visits The Deep End, a nightclub owned by her teenage son Beau's older, scummier gay lover Darby. When a club worker announces the fabulously thin and stylish Margaret as "someone's mom," I have to laugh. Margaret wants Darby to stay away from Beau. Demonstrating awesome listening skills, Darby visits Beau at night at his Lake Tahoe shorefront home. They argue. Beau runs away and Darby accidentally falls into the lake.
The next day, Margaret finds Darby's dead body on the shore, with an anchor in his chest. Finding a piece of Beau's ripped clothing on Darby, Margaret suspects her son killed him. She transports the body by boat and dumps it in a distant cove. Wouldn't you pick the middle (and deepest part) of the lake? She returns home only to find Darby's car incriminatingly parked in front of their house. She boats back to the cove and swims to retrieve the car keys from the dead man's pockets. A task only a mother could love.
Margaret asks Beau what happened the previous night. Conflicted over his sexuality, Beau refuses to talk. Margaret mistakes his silence for guilt and stays silent over the cover-up herself.
Alex Spera shows up looking for Margaret's husband Tom. Tom is stationed far away on an aircraft carrier and Margaret must deal with Alex by herself. Alex blackmails her for $50,000 over the connection between Beau and Darby, whose dead body has just been discovered. Proof of the connection is a home video of Beau and Darby having sex. Margaret tries without success to raise the money within the deadline given her by Alex and his older, scummier partner in crime Carlie Nagel. When Margaret misses their meeting, Alex returns to her home, only to find her trying to save her father-in-law Jack from a heart attack. Alex performs CPR on Jack. Hmm. Could he have learned it watching Goran Visnjic play doctor on TV's ER?
Having bonded over a heart attack victim but pressured by Nagel, Alex leans on Margaret again for the cash. Margaret reminds him she is a soccer mom and has greater concerns than meeting the needs of criminal underworld types. She must ferry her kids to baseball and ballet practice. Amazingly, Alex gets soft-hearted (and soft in the head). He tells Margaret that she need only come up with half the blackmail money for Nagel, because he doesn't want his share anymore.
Margaret meets Alex with the little money she has been able to raise. He tells her the police have arrested another man for Darby's death. Margaret has a poorly-timed attack of the guilty conscience and tells Alex she killed Darby. Instead of revealing Margaret's claim to Nagel, Alex tells him it's over.
Nagel goes to Margaret's home and demands the money. He begins beating her up but Alex shows up. The men fight and Alex kills Nagel. Bleeding from the fight, Alex drives off with Nagel's body. Margaret attempts to follow but stymied by manual transmission, she enlists Beau to drive her.
Margaret finds Alex has driven off a cliff but despite wearing heels, she scrambles down to be with him. Alex gives her the sex tape and her money and tells her to leave before the authorities arrive. She has a breakdown as he dies. Of course, since tall, dark and handsome Alex had great taste in shoes. Oh, and I think Margaret and Alex might have fallen in love. Beau watches his mother crying over another man and assumes she's been having an affair. Later, Margaret cries more and Beau gives her a hug and tells her she doesn't have to say anything. The phone rings and it's Margaret's husband Tom.