His room

Prudence stood there, shaken to her core, trying to comprehend what she had just done. She had her time to do the right thinking process and her mind had been screaming at her to not use that glass piece, yet she had gone ahead and almost stabbed Vincent with it. 

Vincent stood so close to her frozen body he could take the whiff of her blood, which her frantically beating heart was pumping through her. 

His eyes moved to the side as his face was beside her ear. He saw the rectangular bathtub built along the wall and he already knew what he was going to make her do. "You know," he whispered against her ear, "I was expecting you to stab me with that, or else I would have been very disappointed in you." There was a reason he chose her from the pack of sheep around him that day at the party. Prudence has been living up to his expectations very well, digging a deeper pit for herself to fall in.