He balances “Heart-Shaped Box” between reality and fantasy in ways that threaten to run the book into an uncharted dreamscape, and away from the palpable suspense on which it thrives. But he holds the italics to a minimum, pulls back from the brink of hallucinatory overkill and mostly keeps this story tightly on track. Even when it erupts into strange, violent visions — as when, in the midst of a struggle to the death, light pours up from a newly opened door in the floor — this book is so visually intense that its energy never flags.