The premise of Sliding Doors is instantly appealing, since everyone wonders how his or her life might have turned out differently as a result of different choices. So imagine the mind-bending realization that even missing the Tube by two seconds could alter the trajectory just as radically. It is indeed radical for Gwyneth Paltrow, once again affecting a mostly flawless British accent, whose character ends up with a whole new hair color, career focus, and beau, depending on who's influencing her thoughts -- her sensible girlfriend or the cheating bloke she didn't quite catch with his pants down. Having the two Paltrows inhabit the same London is clever, though it begs unanswered questions about whether the film posits a supernatural dual reality, or a second reality that's only imagined. Fresh enough to still disappear into a role, Paltrow has a fun time with her alternately playful and pissed off Helen. John Hannah exudes good will and charm (especially when he's rattling off Monty Python) and Douglas McFerran steals each of his scenes as the best mate of John Lynch's philanderer. Faced with a new ridiculous scenario each time Lynch meets him at the pub, McFerran dissolves into hysterical derisive laughter any time he tries to give advice. The one distasteful ingredient is Jeanne Tripplehorn's American "other woman," whose brassy scheming sabotages the relative subtlety of the rest of this flight of fancy.