"You have the role of lackey. Maybe collateral, if it comes to that." Barty stopped by the door and used a quick 'alohomora' to open it, then looked inside. He supposed he should teach the boy something useless, so he pointed. "Do you see the red light blinking? It's a muggle alarm system. Uses electricity. Not much less effective than magic, really. It's dangerous to underestimate muggles."

That said he muttered another spell and the red light died down. "Go inside, Malfoy. Quietly."