I don’t envy today’s kids. Aside from enduring an all out barrage on their overloaded senses, most lack the adult guidance necessary to help them navigate perils they can barely identify, let alone understand. It’s just this sort of double jeopardy that the five youngsters in Scott Smith’s gripping “Rollercoaster” face. The troubled teens have stolen a teacher’s car, escaped from their group home, and alighted at Wonderworld, an abandoned, semi-functional amusement park. At first, we feel nothing but loathing for these obnoxious mutants. Then we lighten up somewhat when we realize that Sanj, Stick, and Justin are primarily just there to play hooky and raise a little hell. It’s when we learn that Justin’s big brother Darrin (Kett Turton) and his pregnant girlfriend Chloe (Crustal Buble) plan to swan dive into oblivion from the top of the old wooden rollercoaster at day’s end that the film begins to toss us about like riders on a runaway Tilt-A-Whirl. As if that horrible knowledge wasn’t enough to cast a pall on the day’s proceedings, Stick (Brendan Fletcher) endures a sickening encounter with a pasty-faced security guard, Justin struggles to accept his estranged brother’s plan and Sanj and Chloe nurse a dark secret of their own. So much intrigue, so few years. It’s this realization, that life is so accelerated for today’s kids, it disproportionately magnifies their triumphs and woes, that propels this SXSW Narrative Feature Film Winner. The cast of “Rollercoaster” turns in utterly believable performances. DP Bob Aschmann helps them out, creatively covering every nook and cranny of the amusement park and, in essence making it a sometimes magical, sometimes creepy character in its own right. Finally, to his credit, Smith never tips his hand. We never know whether Darrin and Chloe will in fact leap from the coaster at the designated time, making that harrowing final climb up the rickety wooden steps all the more heart-pounding. Only the film’s matter of fact ending clanks off the rim. Although it might reflect the dispassionate way today’s kids would handle the day’s traumatic events, it’s not much of a pay-off for audience members who, thanks to “Rollercoaster’s” compelling storytelling, have emotionally invested themselves in these kids’ lives.