A new mystery unfolds when Emily and Sam get a new neighbor! Emily and Sam are excited to see a moving van next door, but the new neighbor isn't quite what they were hoping for. He doesn't have any kids, seems grumpy, wears a weird white lab coat, and he keeps getting heavy boxes delivered to his garage. Could he really be a mad scientist? And could he have something to do with their friend's missing dogs? The siblings can't accuse him of anything without evidence, so they set out to use the scientific method to prove he's up to something. The second chapter book in the Emily and Sam series offers opportunities to investigate alongside the siblings to solve the case of the mad scientist next door!