His eyes widen and he jumps back a little when Sherlock identifies the white powder in the bag. Sherlock would have anthrax just lying around.

"I feel like that's still too extreme," Malcolm says. "They'll suspect something's up. Plus I don't want to use anything that might actually hurt someone." He eyes the bag in Sherlock's hands. He's handling it pretty casually. Maybe it's just flour? "Maybe we can force some kind of required fire drill? Or at the very least make the fire alarm go off?"