Mary Reynolds, a dialect coach, is accosted at a cafe by a homeless man, while another man switches out her cigarette pack. Deeks and Eric interrogate Artem Fedor in prison, and he tells about a plan to assassinate Mary, who is now hospitalized in a coma. Callen and Hanna interview her daughter Alex, from whom she has been estranged. Blood tests reveal that Mary, previously known as Katerina Polunin, was poisoned with Polonium 210, the FSB's poison of choice. Hanna and Callen seek advice from Arkady, who claims he doesn't know Katerina. Gunmen seek to kill Katerina at the hospital, but Callen's father Garrison shoots one of the gunmen, with the other fleeing. Katerina was Pavel Volkoff's mistress and stole millions from him back in the Soviet Union, and Volkoff wants her dead. Garisson, who was Katerina's handler for the CIA, is in town to protect Katerina, who dies from the poison. Deeks and Eric are unable to stop two men from kidnapping Alex from the cafe where she works. Hetty tells Garrison that he should tell Callen his history. Garrison slips away from the Boatshed, but Callen had put a tracker on him earlier. Alex gets let go, but Garrison has been captured by the FSB, as Volkoff is still trying to recover his money. Callen and Hanna track the cel signal to where Garrison is being held, and they take out the two gunmen. Garrison had donated the money to charity decades before. Garrison and Callen visit Hannah's grave. Garrison tells Callen that he severed ties with his children to protect them. Garrison tells Callen that Alex is his daughter and Callen's half-sister.