I'll be the contrary voice and say Horowitz's adult work doesn't always land for me, though I know that's unpopular. His 'Magpie Murders' and 'Moonflower Murders' are obviously the big ones, these clever novel-within-a-novel meta-mysteries. They're smartly constructed, no doubt, but the pastiche can feel a bit academic, like a very elegant puzzle box. The pleasure is in the artifice more than any gut-level tension. I found myself admiring the craft more than being genuinely unsettled or thrilled.
For a more straightforward, modern thriller kick, I actually think the first Hawthorne book, 'The Word is Murder', works better. The fictionalized Horowitz as the bumbling narrator is a fun gimmick, and Hawthorne has a decently sharp edge. It's quicker, less ornate. His newest one, 'Close to Death', is fine, but the series formula is starting to show its seams. Honestly, if you want pure, unadulterated thriller momentum from him, maybe check out his earlier Bond continuation novel, 'Trigger Mortis'. It's slick and propulsive in a way his more literary puzzles aren't.