Scarier than anything they experienced in "Titanic" are Kate Winslet and Leonardo DiCaprio's characters, April and Frank Wheeler, of the exaltedly tragic "Revolutionary Road." Adapted by Justin Haythe from the Richard Yates novel, "Revolutionary Road" is about the stultifying conformity of suburban America, the then-fledgling corporate-suckled amorality of the Cheever-ville class and a tantalizing illusion of freedom. But while comparisons to AMC's "Mad Men" are going to ring clear, and somewhat true, Yates' story is an epic all its own, and the performances by Winslet and DiCaprio are car-wreck captivating.