Task: Question Answering
Input (English): Passage: Three years after the events of the previous film, ex-CIA operative Frank Moses tries to lead a normal life with girlfriend Sarah Ross. He dismisses Marvin Boggs' claims that enemies are still after them; Marvin drives off and his car explodes. Although Frank is unconvinced Marvin is dead, Sarah convinces him to attend Marvin's funeral where he delivers a tearful eulogy. Government agents interrogate Frank at an FBI Yankee White facility. Corrupt agent Jack Horton and a team of private military contractors ambush the facility; he threatens to torture Sarah until Frank gives him the information he needs. Frank evades Horton, and with the help of the still living Marvin, goes on the run with Sarah.
Marvin explains he and Frank have been targeted as members of Operation Nightshade, a clandestine operation during the Cold War to smuggle a nuclear weapon into Russia. Horton convinces international agencies that Frank and his associates are terrorists on the run. Frank's old ally Victoria notifies him that she has been contracted by MI6 to kill the fugitives. Another top contract killer, Han Cho-Bai, is also hired, seeking revenge against Frank.
Frank, Marvin, and Sarah steal Han's plane and fly to Paris to find "The Frog", with the Americans and Han in pursuit. They are met by Katja Petrokovich, a Russian secret agent with whom Frank had a relationship, who is also investigating Nightshade. They interrogate the Frog and Sarah, hoping to one-up Katja, seduces him. 
Question: Who is Ketja Petrokovich interrogating?
Output (English): Nightshade.