Xanthas notes that the grate has been sealed by cement from the outside, and there is a large iron lock, that looks new besides.
Trying to pick the pock, Xanth grumbles about the amoun tof light, and the lack of proper equipment, and finally just tryes to break it. After a few attempts, the lock gives, but not beofre making alarge enough racket that the guards below start to look around as if wondering what caused the noise, one inparticular looks to the grate where the characters sit.