Title: The medallion mystery
First published: 1994
Description: Billy and Shawn's timetable for visiting the planet Lios changes after Shawn is taken hostage by space criminals.
Subjects: Fiction, Extraterrestrial beings, Science fiction, Adventure and adventurers, Children's fiction, Mystery and detective stories, Rio grande river and valley, Fortification
LC classification: PZ7.H3685 Me 1994