-Alexis asks Castle for help when she believes the subject of her Innocence Review, death row inmate Frank Henson is truly innocent and only has 72 hours to live.
-Alexis and Castle take a road trip out to Pennsylvania and find trace evidence that shows that Kim, the murder victim uncovered a meth house and was about to turn in a student she was tutoring. Castle thinks that student was Frank's brother John.
-With Beckett's help back in NYC, they find out that Frank has been covering for his brother out of guilt for the head injury he gave his brother during a car accident where he was driving. But it turns out neither brother is guilty.
-A swimming team charm left at the scene helps prove that another student, now a police officer in town was actually the killer and Frank is set free.
-Alexis makes up with her father and thanks him for his help. Then she goes back to NYC and thanks Beckett for her assistance. The two share a heartfelt hug.