question: Who is the brother of the boy the sergeant befriends?
context: Suddenly, London goes dark and loses all of its electricity.  There is commotion at a cinema, with people demanding their money back.  The owner of the cinema, Karl Verloc, enters through a back entrance to the living quarters above, and pretends to have been asleep and not know anything of the blackout.  His wife, Mrs. Verloc comes to get him and is surprised to see him, but he informs her that he had been sleeping the entire time.  He instructs his wife to return the money to the customers – against her protests – because he has "some money coming in."  As the money is about to be disbursed to the customers downstairs, the lights go back on.  It is revealed that sand was put in the boilers as an act of sabotage on London's electricity grid.  
  The next day, Verloc meets with his contact and it is revealed that he is part of a gang of terrorists from an unnamed European country who are planning a series of attacks in London, though their exact motives are not made clear. Verloc's contact is disappointed that the newspapers mocked the short loss of electricity, and instructs Verloc to place a parcel of "fireworks" at the Piccadilly London Underground station.  Verloc tells the contact that he is not comfortable with any act that would cause the loss of life.
  Meanwhile, Scotland Yard suspects Verloc's involvement in the plot and assigns Detective Sergeant Ted Spencer to investigate Verloc.  Spencer is initially undercover as a greengrocer's helper next to the cinema, and befriends Mrs. Verloc and her little brother, Stevie, who lives with them, by treating them to a fancy dinner.  At this point, Spencer and Scotland Yard are unsure whether Mrs. Verloc is complicit in the terrorist plots or merely innocently unaware.
answers.text: Mrs. Verloc