Man, picking a single 'best' is tough because she cranked out so many classics. For pure, clockwork suspense, I always circle back to 'Where Are the Children?'. It’s her debut, but the premise is just brutally efficient—a woman with a buried past finds her new children missing. The pacing feels like a tightened spring; there’s no extra fat, just relentless forward motion. It established her whole blueprint.
That said, 'A Stranger is Watching' hits differently. The dual-timeline thing, counting down to an execution, with a victim trapped in the same building... It’s almost claustrophobic. Some readers find the 70s/80s setting dated, but I think that adds to the isolated, technology-free terror. The tension is less about whodunit and more about the visceral race against time.