 What is the conspiracy Retief is trying to uncover?
"Mr. Retief, those are just the sort of questions we avoid with the Groaci. He looked at Retief and froze in mid-motion, a metal tube poised over a waiting pot. Retief backed into the opening to a narrow crossway and offered further verbal familiarities to the drunken local, who followed, furious. Retief backed, rounded a corner into a narrow alley-like passage, deserted, silent ... except for the following Groacian. Two Groaci wearing heavy eye-shields and elaborate crest ornaments indicative of rank rose as Retief entered the room. "I can talk no more of this matter—" "You'll talk to me, or there'll be a task force here in five days to do the talking," Retief said.
 Nine years ago, a Terran cruiser landed on Groac but soon mysteriously disappeared, along with its entire crew. Retief wants to find out what happened to the ship and its crew.
 Nine years ago Groacians invaded Earth and stole a Terran space cruiser. Retief wants to find out what happened to it.  Nine years ago, Consul Whaffle mysteriously disappeared from his government office. As the new consul, Retief feels it is his duty to find out what happened.  Nine years ago, a Terran cruiser landed on Groac but soon mysteriously disappeared, along with its entire crew. Retief wants to find out what happened to the ship and its crew.  Nine years ago Terrans came to Groac and attempted to take over the existing government, but failed. During the skirmish, a Terran cruiser disappeared. Retief wants to find out why the siege failed and what happened to the cruiser.