The great Metropolitan Observatory was the pride of 22nd century engineering and science. When the astronomer Dr. Henry Brunner was found there, battered and strangled to death, there were four suspects with reasons to hate him: his immediate assistants, and the janitor who owned a fantastic Martian spider pet... Scientific detective Adam Quirke was called in to investigate the seemingly insoluble mystery. What was the connection between the star Betelgeuse, which Brunner had been studying, and the astronomer's murder?