"OK, so Jimmy Stewart is sitting in his DeSoto right where that white minivan is parked — right there!" says author Aaron Leventhal, as knowledgeable an Alfred Hitchcock fanatic as you are bound to find. "And he's looking between those two pillars — right over here — at Kim Novak, who's coming out of her apartment building to get into her green Jaguar and go wandering through the city." We're standing at the corner of Mason and Sacramento streets atop Nob Hill in San Francisco, and we're about to follow, 50 years later, in the footsteps of Stewart, Novak —...