From the introduction:
Tasked with retrieving a meteorite from the planet H’Catha, the characters and their fellow Spelljammer Academy cadets boarded a derelict tyrant ship (a stone vessel built by beholders). After installing a spelljamming helm aboard the ship, the characters ran into some trouble.
A fire aboard the tyrant ship killed the characters’ supervisor, Petty Officer Ryeback. An investigation revealed Cadet Miken Haverstance to be the saboteur. After his capture and interrogation, Miken told the characters that he’d been hired by a mercane (a blue-skinned giant), who holds a grudge against one of Spelljammer Academy’s founders, Mirt the Merciless. The mercane’s name is Vocath, although neither Miken nor the characters are aware of this fact.