On Writers Helping Writers:

Unputdownable stories keep readers off balance, as one scene tips into another, and another, and the next. Each scene’s challenge demands a response, and each response spirals into fresh complications.
But compelling stories don’t pile on problems in random fashion. Complications flow organically from one scene to the next in a chain of action and reaction. The upshot for your novel? This chain of progressively escalating complications transforms a mere assemblage of scenes into an unstoppable narrative.