Unfortunately, the Prince did see the Captain hiding in the alley.  As he had missed something earlier that evening, he was more on alert than usual.  He nearly considered just ignoring her, needing to distract himself with his duties, and so kept walking.  But when he heard her bolt, stumbling in the direction of the castle, he stopped and turned around.  Noting the blood on the door, he strained his senses as he entered, slowly following the trail left behind, hoping he wasn't too late.