Complex sentence: They were forced to identify random objects from within the keep for a Sister of the Dark or they would be forced to listen to the screams of children being tortured while their parents begged them to give up the information.
Split into simpler sentences: They were forced to identify random objects from within the keep for a Sister of the Dark. If they refused to do so, they were forced to listen to the screams of children being tortured while their parents begged them to give up the information.