There is a decidedly neo-Hitchcockian bent to the tension-packed "The Deep End," a daylight-noir suspense thriller that stars idiosyncratic indie empress Tilda Swinton as a Lake Tahoe soccer mom attempting to cover up the death of her gay son's oily older lover.Margaret Hall (Swinton) finds the man's body near their lakefront boathouse with an anchor buried in his chest and, with her instincts racing faster than her logic, jumps to the conclusion that her confused teenage boy (Jonathan Tucker) was responsible for his demise.She drags the body into a motor boat, chug-chugs across the lake and dumps the corpse in a cove before realizing how her hasty assumption and even hastier reaction could lead to her undoing. The man's car is parked outside their house, and a videotape surfaces of her son in bed with the dead dude -- hand-delivered by a blackmailer demanding $50,000 within 48 hours.There are several parts of the plot that just don't hold water. Why does she row all the way across the deepest lake in North America to dump the body in six feet of crystal clear water? Why does she let the blackmailer into her house when he just shows up on her doorstep and doesn't identify himself? Why doesn't she just ask her son what happened, and upon discovering the truth go to the police?But while it's impossible to avoid second-guessing Margaret's frequently stupid choices, Swinton sells her motherly motivation and sells the fact that, in a panic, she makes mistakes -- big mistakes.Co-writers and directors Scott McGehee and David Siegel (1993's "Suture") adapted the story from Elizabeth Sanxay Holding's novel "The Blank Wall" (adapted once before in 1949 as "The Reckless Moment" with a hetero daughter instead of a gay son), adding many of their own touches including the scenic location and a notable ability to make even a beautifully photographed, bright, clear day in Tahoe exude a foreboding trepidation.The beautiful, slightly reptilian Swinton contributes greatly to tying the viewer's stomach in knots by applying to this everyday mother that trademarked harried intensity she's brought to the eccentric roles that have made her reputation in films, like "Orlando," "Female Perversions" and "Conceiving Ada" and, of course, later great performances in "We Need to Talk About Kevin" and "Suspiria." When Swinton flits around nervously on the screen, considering how far she's willing to go in this cover-up, the same agitation is viscerally visited upon the audience.McGehee and Siegel twist some emotional chaos into the film's growing tension when the resolve of the handsome blackmailer ("E.R's" Goran Visnjic) begins to fluctuate. Increasingly aware that Margaret is truly unable to meet his demands, he's also beginning to feel compassion (and perhaps something more) for her. But his murderous partner (Raymond Barry) will have none of it and muscles Visnjic to go forward with their plan, conscience or no conscience.If it weren't for the recurring common sense and police investigation loopholes that the filmmakers have annoyingly chosen to ignore (the list appearing earlier in this review is considerably abridged), there would be little to distract from the chilling tingle "The Deep End" emits constantly.