Ben's repulsive cousin, T.J., comes to stay. He discovers an incriminating videotape of Agent Z activities and blackmails Ben into becoming his slave.Meanwhile, Ben, Jenks and Barney embark on their first film, entitled Invasion of the Killer Bananas, in which T.J. unwittingly has a starring role. When T.J. disappears, however, the film points towards Ben, Jenks and Barney as murder suspects!In an attempt to clear their names, the boys use all the cunning of Agent Z to try and lure T.J. home and into the hands of the police . . .Mark Haddon has a sharp understanding of what makes children tick, and they will delight in the ever more daring, ever more hilarious missions of Agent Z and his three creators.