Hetty was ordered to abort the rescue mission at the last minute. Some time later, George himself was murdered with his daughter, Clara attempting to flee to the United States with her two young children with the assistance of Henrietta Lange who was Clara's handler. He later killed members of the Comescu family who had committed war crimes, resulting in the remaining Comescu members beginning a blood feud where they vowed to kill every single member of George's family in return.
In World War II, Callen's grandfather, George was an OSS agent stationed in Romania. Born on Main Romania as Grigori “Grisha” Alexandrovich Nikolaev, Callen was the second child of Russian KGB Major Nikita Aleksandr Reznikov and Clara Callen, a half-Roma agent with the CIA with Callen also having an older sister named Amy.