Holmes tells Watson that they are going to do some dangerous work that evening, and after a roundabout trip through the city they enter an empty house, an abandoned building known as Camden House whose front room overlooks—to Watson's great surprise—Baker Street. Holmes's room can be seen across the street, and more surprisingly still, Holmes can be seen silhouetted against the blind: it is a lifelike waxwork bust, moved regularly from below by Mrs. Hudson to simulate life. Holmes employs the dummy because he was seen by one of Moriarty's men, and thus he expects an attempt on his life that very night. Holmes and Watson wait two hours—until approximately midnight—in the abandoned Camden House. A sniper, who has taken the bait, fires a specialized air gun to assassinate his foe. Surprisingly, he chooses Camden House as his vantage point.