The engine that drives any top-notch thriller is plot—and the fuel propelling it is pace. Pacing can be achieved by both structural and stylistic means: short, dramatic chapters that link together and push the action forward; scenes that are stripped down to their elemental, dramatic core; a close-in point of view that compels the reader to experience in real time what the character experiences. Short, unencumbered sentences work well, as do the italics of being inside a character’s mind. And it’s important to invest the reader quickly in what’s at stake.