Alexis is a normal ten year old boy who lives on a roving space laboratory with his parents. One evening they are attacked by a strange spacecraft. Alexis, or Lexi, is fired off into space. He hibernates before being picked up by Tavia, who knows a great deal about him and seems to be able to read his mind. There is trouble with marauders in that sector of space and Tavia takes Lexi to a primitive planet, Thera, to stay with her Great Uncle Relius, and his grandchildren, Chard and Lissa. Lexi learns that he has the same strange blood as the late Emperor, and that Tavia is a member of the Imperial Legion whose job it is to protect the Emperor and his family. The Legion are chosen by their ability to communicate by thought transference, and Lexi finds that he can do this too. Lexi is given a new identity and attends the local Tutor Centre with the other children. His lack of experience quickly gets him into trouble and his own unorthodox ways of dealing with this leads to more. Relius's unusual methods of bringing up children supplement the lessons at the Toot and help Lexi to understand more about the Empire. Just as he is settled in this new way of life the marauders discover his whereabouts and invade the Tutor Centre. He escapes with another member of the Legion but they are caught by the marauders. Lexi carries off a double bluff with the help of an old friend, Xim. The two of them fly to a nearby moon but the inhabitants send him off with some technologically sophisticated aliens known as the Xylion. Lexi gets on very well with the Xylion, but they communicate totally by thought and have no speech at all and he finds that his own mental powers are subtly changed by the experience. He also begins to realise that his father was possibly not quite so distant a cousin of the old Emperor as Tavia had led him to believe. Lexi arrives at the Space Academy, the headquarters of the Legion, and is reunited with Tavia, and later with Chard. The marauders attack and the battle is going badly for the Legion until Lexi summons assistance from the Xylion. The fighting over, he goes to talk to the marauders to find out exactly what it is they are demanding. He is then able to engineer an agreement that restores peace to the galaxy. At last Lexi can go to Earth to rejoin his parents, however once they are there Tavia has to break it to him that his father died after the initial attack. They arrive at the imperial palace on the banks of Lake Geneva where he is surprised to find that not only is the new Emperor a woman, but she is his mother.