Sam pushes the door further open, but has to let go of it when William decides to take off after Janet and she grabs him just in time to see the door shut behind them. "Too late for that," Sam says, trying the door. It won't open. She's not too bothered by this; this sort of thing is par for the course, so to speak. Just in case, though, she scoops William up and carries him, even though he's heavy now.