Even the coolest stars sometimes get hot under the collar. Take John Travolta. Something happened on the Paris set of The Double — creative differences with director Roman Polanski, perhaps? — that had him beelining it back to the U.S. Chilling out in Los Angeles, the AWOL star explains what made him bolt in our exclusive cover story. Then there’s the always bracing James Caan, who’s orchestrating a Travolta-caliber comeback as the over-the-top villain in Arnold Schwarzenegger’s latest blowout, Eraser. And Bound‘s fiery Gina Gershon, who proves that it’s possible to have a career after Showgirls. And Tin Cup‘s Rene Russo, who proves that it’s possible to steam up the screen after 40. And 15-year-old Natalie Portman, who proves that it’s possible to be a movie star after school. Also playing it cool in these pages: Heather Matarazzo, the ultimate geek-chic girl since her wrenching debut in Welcome to the Dollhouse; the Fugees’ Lauryn Hill, a hip-hopper who refuses to take the usual rap route to the top of the charts; and Joi, the cool mama of the funk underground. Need an icy blast? Then check out our special section on the concept of the moment — extreme — which has everyone from Ralph Lauren to your local telephone company pushing the cultural envelope to the max. Read on…and stay frosty.