-Susanna Richland, an accountant is found with stigmata type wounds to her hands and a stab wound from a sword through her throat. She was researching symbols the Freemasons used around the time of the Revolutionary War.
-Susanna was actually a part of a contest. She'd managed to put together the clues to fine a treasure the Freemasons hid in secret chamber in a chapel. Castle and Beckett follow a monk who leads them to the chapel and Castle figures out the clues to open the chamber. They realize that is where Susanna was originally killed.
-The Director who ran the contest admits he hoped that a contestant would lead him to the treasure but he didn't kill the victim. That was her cousin, Henry who wanted the treasure for himself and was furious when Susanna told him she planned to donate it to a museum.
-Castle and Martha have dinner at Alexis and Pi's new place but Castle can't hide his disapproval for Pi and their living arrangement. Later he goes to apologize but Alexis won't let him in.
-Alexis is upset that she heard about his engagement from Martha. She isn't sure about Beckett but she'll accept her and she expects the same from her father about Pi. She says she needs time to get over being mad at him and he needs time to accept her and Pi. Then she closes the door on her father.