A stone like any other, lying in a whorl of sleet and mud. Maybe there's something under…

A stone like any other, lying in a whorl of sleet and mud. Maybe there's something under it?

Ignore it. [Leave.]

Turn it over.

There's a key beneath it, rusty from the dirt.

"This must be for the front door. Pity it doesn't have the apartment number on it. This building has hundreds of apartments."

"How are we going to find the right one?"

"We'll just have to go in and see."

Put the stone back. [Leave.]

"This must be for the front door. Let's see if it works."

Looks like it could belong to the building's front door.