This is a description: A 7-year-old boy with an injured back from an accident four years ago that prevents him walking is taken for a change of air in the Mediterranean. When they are on the Nile, a young man comes to the yacht to introduce himself to the family because his father had known them, but when he finds that Fen has been left onboard with his caregiver while the family is sightseeing, he decides to pose as the genie Siddereticus. Fen is enchanted at having his very own genie. Siddereticus magically produces scarabs at the first meeting, gives him an amulet later, sings for him, and provides other small gifts, all of which delight the boy. When they sail for Venice, Fen is worried that he will not see Siddereticus again, but the genie shows up there. The young man decides to follow and continues to act the genie for Fen when the family goes to the Bay of Naples to meet his Aunt Cynthia. Throughout the story, the young man's actions raise Fen's spirits.
I thought it was a fun, easy read.