Originally, these tasks weren't supposed to be handled by the Anti-Terrorism Team, but there was no choice. There weren't enough people on site, and they were from out of town, so relying on just Barney and his few men wasn't going to cut it.
Jimmy had already returned to the main building. After searching a few rooms, he called Barney to the study, "Barney, there might be a hidden chamber here."
Jimmy pointed under the bookshelf, where you could see some scratches, "These books were probably knocked off the shelf. Look at this—there's something behind the bookshelf."
Barney and Jimmy both drew their guns, called over two people, and moved the bookshelf slightly out of the way. A hole appeared in the wall, revealing a passage downward, but they couldn't see what was below.
This was quite the surprise. Barney stood at the hole looking down; there were fixed steel bars along the wall that served as steps. He looked around, "I'll go down; you guys cover me from up here."