Reese is recovered and leaves Finch and his team, heading to Colorado, but they do not know his whereabouts. The Machine delivers the next number to Root, and Finch is surprised to see how she can communicate with The Machine. He gives the name of the IT consultant Arthur Claypool to Shaw, who has a terminal brain cancer. Shaw poses as a doctor and sees that Claypool has three secret agents protecting him. She talks to Claypool and sees that he has memory issues and is unable to recognize his wife Diane, who has been married with him for twenty years. When Claypool is sent to the radiology room, she sees sodium pentothal in the trash and the false technician interrogating him. She protects him but is arrested by the agents and locked in a room. When the agent arrives to interrogate her, he faints, and Finch tells her that the Vigilance is trying to abduct Claypool. She goes to Claypool's room and finds the other agents unconscious. She asks Diane to help her to dress Claypool to escape, since they are in danger. Finch drives the getaway car and heads to a safehouse. Soon Shaw learns that Finch and Claypool studied together in MIT. Claypool remembers their time together and discloses that he has built a machine name Samaritan. They question him why he did not recognize Diane and they find the truth. Meanwhile, Fusco has tracked Reese down and is in a bar with him, but Reese does not like he found him.
"Lethe" is another great episode of "Person of Interest", where the viewer learns that there is a second machine built by an old Finch's friend that also attended MIT. The plot has action, but the final twist certainly surprises any viewer. The subplots are irrelevant but help to build the characters. My vote is nine.
Title (Brazil): "Lethe"