This collection of excerpts introduces a vibrant, ocean-covered planet called Coralee, a popular destination for explorers and romantics, with human and Dreekan colonists coexisting. A cable-laying platform, the Hyperion Dawn, is attacked by unknown creatures, the Krill, initiating a desperate struggle for survival against these genetically engineered living weapons. The Doctor and Ace arrive, initially seeking a holiday but quickly becoming embroiled in the colony's defense, uncovering a deeper conspiracy involving the Cythosi who secretly plan to harvest the Krill for their own purposes as a weapon against their enemies, the Zithra. The narrative follows their efforts to protect Coralee while battling both the Krill and the manipulative Cythosi, ultimately leading to a stormy climax and the colony's recovery after significant losses.

Ask this episode

“What did the council decide on item 42?” — answered with the speaker and the moment.