An understandable sensation in the Midnight Madness section of the 2011 Toronto International Film Festival, dynamite horror indie "You're Next" was promptly bought by Lionsgate before sitting on the shelf for nearly two years. The wait might have been long, but for a movie that allegedly cost under a million dollars to make and is seeing a wide theatrical rollout on 2,400 screens, it makes little difference how much it grosses for it to be considered a huge success. Inspiringly directed by Adam Wingard and cunningly penned by Simon Barrett (collaborators on the spooky jack-in-the-box "Phase I Clinical Trials" segment of 2013's "V/H/S/2"), "You're Next" is the most exciting piece of work within the genre all year, a film that revitalizes the home-invasion thriller in unexpectedly vibrant ways while giving masterfully sly nods to vintage '70s and '80s Carpenter-esque synth scores and quintessential classics such as 1974's "The Texas Chain Saw Massacre," 1978's "Halloween," and 1984's "A Nightmare on Elm Street." Not content to simply ape other films, Wingard and Barrett cook up a unique identity in their stylish approach to the material and their treatment of characters who would be interesting enough for the viewer to want to watch even if they were transplanted into, say, a straight family drama. If that weren't enough, Sharni Vinson (2010's "Step Up 3D") instantly belongs in the same company as Jamie Lee Curtis, Heather Langenkamp and Neve Campbell, a willful, determined, dynamic horror heroine for the ages.

Paul (Rob Moran) and Aubrey Davison (Barbara Crampton) have invited their four grown children—Crispian (AJ Bowen), Drake (Joe Swanberg), Aimee (Amy Seimetz) and Felix (Nicholas Tucci)—to celebrate their thirty-fifth wedding anniversary. With their significant others in tow, they convene at their family's secluded mansion in the country. It doesn't take long for sibling bickering to commence at dinner, but their petty arguments are rudely interrupted when an arrow pierces the head of one of the guests. Accosted by three masked figures—a lamb, a tiger, and a fox—the family become trapped prey, the body count skyrocketing among them as they're systematically sliced and diced. Things look bleak for sure, but Crispian's graduate student girlfriend, Erin (Sharni Vinson), has a little secret about her past that might make her these killer's most formidable match.

Oftentimes, slasher pictures of this nature hit close to home—everyone can relate to fears of strangers invading one's private space and lives—while becoming subjective studies in doom and gloom. "You're Next" is seriously intense at times and the premise is a naturally dark one, made all the more persuasive by the unusually realistic ways the different family members react when faced with such wrenching circumstances, but the experience of watching it is far from glum. Poppy and assured, the film introduces its characters with economical snapshots of lives in progress—a loaded dysfunctional history between the family members brings added weight to the goings-on—before preparing to pounce. When the killers finally show up, there is scarcely any letting up. And, when the tables turn midway through and Erin comes clean about why she's so knowledgeable about extreme situations such as this, the movie transforms again into a brutal, thrilling crowd-pleaser.

Contrary to popular opinion, it's fun seeing people in horror flicks who are savvy and smart, making more right decisions than wrong when their lives are in danger. At the same time, there is a certain human fallibility that comes into play. Thus, while Erin tries to assess the situation rationally, Drake's wife, Kelly (Sarah Myers), is hasty in her decision to get out of the house and seek help from the closest neighbors. Drake and Crispian, who are always at each other's throat, make a go at putting their disagreements aside. Meanwhile, mother Aubrey closes down in shock and grief when one of her kids is killed, while Aimee—always trying to compensate and please her parents and siblings—makes a brave but stupid decision that could cost her dearly. As for patriarch Paul, he wants revenge, his ideas about safety shaken to their core when he makes a discovery that the intruders have been hiding in their abode for days, patiently lying in wait. It's a fascinating dichotomy between loved ones and acquaintances that gives a welcome extra layer to what, in lesser, more frequent instances, is apt to devolve into a thematically empty chopping-block procession.

Sharni Vinson gives what should be a breakthrough performance as Erin. A lot is asked of her in this role, which requires emotional vulnerability as well as physical and intellectual aptness, and she more or less carries the film through the rousing second half. There isn't a moment where the viewer isn't on her side, one's sympathy at attention. It warrants mentioning that Erin may be learned in the ways of survival, but she is far from invincible. Her struggle, as it were, is ours. The unconventional rest of the cast will probably not be familiar to casual filmgoers, but anyone who knows their current indie directors, character actors, and horror veterans are certain to be delighted by this line-up. AJ Bowen (2010's "Hatchet II") is becoming a current-day horror staple, and his part as eldest brother Crispian is the juiciest of his career, to date. Joe Swanberg (whose own directorial effort, "Drinking Buddies," is being released on the same day) is perfectly smarmy as Crispian's judgmental brother, Drake. Usually seen playing downbeat, downtrodden types, Amy Seimetz (2013's "Upstream Color") impressively changes things up as Aimee, her bouncy exterior a defense mechanism to shield her insecurities having grown up in a family of boys and never measuring up. Rob Moran (2011's "Hall Pass") plays it low-key but all the more memorable for it as father Rob, just trying to hold on and protect his wife and kids as well as he can. And, as mother Aubrey, it is a treat to see Barbara Crampton (best-known for her work with Stuart Gordon in 1984's "Re-Animator" and 1986's "From Beyond") onscreen again, her shattering portrayal of motherly anguish at the sight of what she cares for the most falling apart a lingering force even after she's exited the scene.

"You're Next" opens with a post-coital prologue that finds a dumpy middle-aged guy (Larry Fessenden) heading to take a shower while his younger, casually unimpressed girlfriend (Kate Lyn Sheil) makes her way downstairs. Partially naked with only an unbuttoned shirt barely covering her breasts, she is left exposed by the living room's looming floor-to-ceiling glass windows as she sits and listens to a song from the CD player. Suffice it to say, these two are not long for this world, yet the haunting, echoey 1977 pop-rock ditty—Dwight Twilley Band's "Looking for the Magic"—continues on repeat. Returning again and again at different points in the film, this sonic leitmotif is ingenious verging on unforgettable. There is something insanely eerie about up-tempo music playing over and over in a lonesome home occupied by no one other than two undiscovered dead bodies, and director Adam Wingard milks this for every ounce of jittery effectiveness it's worth. One could say the same in general about the pic's entirety, so superbly conceived and carried out, so draped in tension yet also naturally funny in its tonal command, that it seems nearly impossible not to walk out of the film on a nervy, satisfied high. Horror cinema fans, a word of advice: rally together and absolutely do not let "You're Next" pass you by.