"A born creator of myths, my sister always liked to tell the story of how we were misnamed." I knew from this first sentence that this debut thriller would be something special. For the narrator, Ava, was born minutes after her twin sister Zelda. The alphabet's reversal foreshadowed the sibling pecking order. Zelda is the wild, vibrant, larger-than-life twin. Ava is the buttoned-up, reserved, by-the-book twin. To put it in terms of stress responses, Ava, having spirited herself away from the failing family vineyard to Paris, is flight. Zelda, who stayed behind, is pure fight.

Or at least, that's how it seems on the surface. When Ava gets word of Zelda's sudden and surprising death, she returns home to the family vineyard in upstate New York. Eerie messages from her twin, apparently from beyond the grave, signal the beginning of an alphabet-themed scavenger hunt that might (or might not) prove that Zelda is, in fact, alive. Dolan-Leach plots her twists fairly and with care, and her sense of fun is infectious. There's a winning "let me entertain you" vibe that takes hold.

But I loved Dead Letters most for imbuing its froth-laden surface with real emotional heft. The stakes are high. Ava, following the sequential traps laid by Zelda, comes to devastating terms with what remained in her home even after she fled: family dysfunction, her tendency to hide from troublesome feelings about alcohol and ex-boyfriends and abandonment, and how her sister's love—and multiple betrayals—matter to Ava above all. The playful clues that Zelda leaves for Ava are so much more than standard mystery misdirection. They are a window into the myths a family creates around one another to protect from and draw closer to those we love most—the mysteries that haunt us well after we solve them.