Reese and Carter head to Bishop, Texas, to investigate the cold case of Hannah Frey, who disappeared after leaving a library 20 years ago. Reese is convinced that Hannah is actually Root and hopes to locate Finch by uncovering more about her past. Meanwhile, Root forces Finch to watch as she tortures Denton Weeks, hoping to uncover the location of the Machine. Finch manages to help Weeks free himself briefly, but Root quickly turns the tables and kills him after extracting the last bit of information from him. Reese and Carter follow the evidence in Texas and eventually discover that Hannah Frey was killed and her body was hidden in Texas, but her best friend Sam Groves later became Root. Using financial information they find during the case, Reese manages to track down Root's credit card transactions to the small town in Maryland where she's holding Finch. He hightails it to Maryland and manages to intercept them at a train station, where Root nearly kills Finch before fleeing the scene. Later, after Reese returns Finch to the safe confines of the library, Root calls to warn him that she will be back.
Back in New York, Fusco is charged with taking care of Reese's new dog, Bear, and with continuing the investigation into the Alicia Corwin murder case. When he stumbles upon a break in the case and overhears Hersh talking about Weeks, he immediately informs Reese, who pieces it all together to find Finch.