Olivier doesn't follow along right behind the group, but gives them a few feet of space so that she can listen to what is going on behind them.

When she see a door coming up to their left, she closes the gap.

"I will stand guard while you search. We should agree on a signal in case there is trouble inside the room or out here. Whistles tend to be a good signal," she suggests, and gives a long, but quiet whistle in example.

"It would be louder of course, but no need to draw attention right now."