The Drone's Empty Drop

Every night at exactly 8:17, a delivery drone drops a package addressed to no one at Killian's building — and every night, the box turns up empty. When Elowen, Killian, and Roland start tracking the drone's flight path on their homemade Casebook app, they uncover a pattern that stretches from a corner pharmacy to a warehouse row along the river.

In a gleaming near-future New York where flying cars glide over 96th Street and robots share the sidewalk with pedestrians, three kids are about to learn that the biggest secrets in the city hide in plain sight — and that some grown-ups would rather they stop looking.

With Officer Julian Reed reluctantly on their side and a mysterious silver compass pointing the way, the detectives race to unravel the routes, dodge a suspicious pharmacy diversion, and triangulate a signal before whoever is behind the empty drops realizes three kids are already three steps ahead.