After escaping the Tlak'khan on a jungle world thanks to Harrison's flying skills (sort of), the team arrives on a sulphur-covered planet and bat-like inhabitants, the Har'un. With his jetpack damaged Harrison accepts an invitation to fly with the locals but doesn't do so well. Determined, Harrison keeps trying but is the only one in the group who can't manage. The planet is polluted due to the Tlak'khan's efforts and they send a team to attack – Harrison has to mount up to warn the others and manages to get the hang of it. the Tlak'khan refuse to learn from their mistakes and fall victim to the Har'un's gas bombs.