"Yes- I've heard it as well."
Desmond approaches Gael and the bookshelf, and violently taps and shoves literally every book in it (he counted them too, there are 19 of them, mostly in alphabetical order) but no cliche secret trapdoor appears.
"Well, let's try this, then." Desmond goes to the lateral side of the shelf, and starts to try to push it. For his surprise, it wasn't that heavy, as he easily pushes it from the wall. Behind it, he sees a discolored portion of the wall with an odd segment jutting out of it. A small crack runs along the center of it.
"You might want to see this." Desmond refers to the rest of the group.