Given the task definition, example input & output, solve the new input case.
In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Example: Passage: Nearing London, Oliver encounters Jack Dawkins, a pickpocket more commonly known by the nickname the "Artful Dodger", and his sidekick, a boy of a humorous nature named Charley Bates, but Oliver's innocent and trusting nature fails to see any dishonesty in their actions. The Dodger provides Oliver with a free meal and tells him of a gentleman in London who will "give him lodgings for nothing, and never ask for change". Grateful for the unexpected assistance, Oliver follows the Dodger to the "old gentleman's" residence. In this way Oliver unwittingly falls in with an infamous Jewish criminal known as Fagin, the gentleman of whom the Artful Dodger spoke. Ensnared, Oliver lives with Fagin and his gang of juvenile pickpockets in their lair at Saffron Hill for some time, unaware of their criminal occupations. He believes they make wallets and handkerchiefs.
Output: Who believes Fagin's gang make wallets and handkerchiefs?.
This question is based on the following sentence in the passage "He believes they make wallets and handkerchiefs". It evaluates the understanding that the pronoun "he" refers to name "Oliver". You can ask questions like this one about most pronouns in a paragraph.

New input case for you: Passage: Novelist Geoff and his wife Sally rent an isolated countryside bungalow to enable Geoff to finish his latest book without the distractions of life in London. On their arrival, they are horrified to find a dead man in the property; before they can report the discovery they are confronted by Duke, a gangland boss, and his henchmen who have, it transpires, been using the empty property as a hide-out for stolen valuables which they are planning to smuggle out of the country. A rival gangster, Juan, also has his eye on the goods and has discovered their whereabouts. The dead man is one of his minions.
Geoff and Sally are held captive, and matters take a turn for the worse when Juan and his men also arrive on the scene, forcing a stand-off between the two factions during which Geoff and Sally are roughly-treated by both sides. Duke starts to fall for Sally, and his obvious interest in her antagonises his girlfriend Rina. Eventually there is a bloody shoot-out between the rival gangs, with Duke's men getting the better of the exchange. Duke boards a plane to make good his escape with the valuables, but the plane is shot down by the jealous and vengeful Rina.
Output:
Who worked for Juan?