The mad scientist next door

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 met...