This is the general discussion post for the episode 4.09 - Sand. Spoilers for the whole series are allowed.
Servalan arrives at the planet Virn - a world covered in strange green sand - to find out what happened to a group of Federation researchers who had gone missing five years ago soon after uncovering a substance with unique energy potential. The Scorpio crew follow her to the planet, curious to find out what she is up to. When Servalan arrives, her ship is disabled and her associate, Investigator Reeve, turns against her. She finds herself alone until encountering Tarrant who teleported down with Dayna to track her. The two must work together to survive and find shelter in a bunker against the green sand, which seems to be a living, intelligent lifeform. Meanwhile, a strange energy storm cripples Scorpio preventing it from performing a rescue.