The Ersatz Elevator by Lemony Snicket

The sixth installment of this series continues to develop the suspense and to create a coherent plot. The Baudelaire orphans are sent to stay with Jerome and Esmé Squalor, and they discover that Esmé is in cahoots with Olaf, knew (and resented) Snicket's Beatrice, and lives across from an elevator shaft that connects to a tunnel that opens under the now-burnt-down Baudelaire mansion. Although the Quagmire triplets have discovered something about Count Olaf with the initials VFD, they don't get the chance to tell the Baudelaire orphans what that something is. These novels get curiouser and curiouser.