Brennan had followed close behind, occasionally checking over her shoulder and looking out for any sign that the person responsible was still around. The fact that Booth was acting the way he was made her realize how serious the situation was, that alone would be enough to convince her but there happened to be a lot of other stuff going on as well.
She waited in the corridor as he disappeared into the room, rubbing the side of her arms absently as she kept an eye out. In her haste to get downstairs and find out what was going on she hadn’t had a chance to grab a jacket or dress ready for a possible outing outside, she hadn’t exactly expected to walk in on what she had.
Once Booth had re-emerged she nodded, but frowned once she had given his words a chance to sink in. “Plan of attack?”