Someone thinks to check for secret doors—especially since it didn't seem like the Hobgoblins used the cloth-covered doorway very much. Everyone must attempt a L2SR on Intelligence.
If no one made the saving roll, then you find nothing. You can return to the fork in the trail, or go all the way back to the intersection.
If anyone made the saving roll, then he found a secret door, and you all manage to open it. There is a long dark tunnel on the other side. Will you enter it?