"You can tell the Internet I'm stocking up on exotic poisons," Sherlock said dryly, but he was smiling. "Right. Back in ten."

The door closed, his footsteps pattered off down the stairs, and then there was blissful quiet in the flat... for exactly two minutes and thirty-seven seconds. All at once John's mobile was buzzing with a text alert and someone was moving back up the stairs to knock on the door--probably Sherlock had taken Lestrade's ID with him instead of his own debit card, the idiot.