*He grits his teeth for a minute, but getting something you want out of Narcissa has never been easy for Sirius. He settles for the politest tone he can muster--it's as if he's reciting from the Auror procedure handbook. It's safer, anyway, than letting himself off the very tight leash he's got himself on now.*

It's setting off the Detector. It's best to let the owner of a house open any locked drawers that set off a detector.