Parts: 5
Writers: Norman Ashby (aka Mervyn Haisman and Henry Lincoln), Derek Sherwin (episode 5)
Airdates: 10 August 1968 - 7 September 1968
Production Code: TT

Doctor: second
Companions: Jamie, Zoe

Creature Feature: Quarks

Story: On the peaceful planet of Dulkis, a group of daring young Dulcians take an unauthorized trip to the Island of Death, a small land mass surrounded by a sea of mist where a nuclear test was once conducted. The resulting destruction caused the Dulcians to ban violence and turn the heavily-radioactive island into a monument to the horrors of war. But the island is not as uninhabited as they think - a ship manned by two Dominators and their servant Quarks has recently arrived, and the Dominators have no moral qualms about killing the Dulcians as soon as they catch sight of them.

When the Doctor, Jamie and Zoe arrive, they meet a Dulcian survey team, also on the island. Cully, the lone survivor of the Dominators' attack, manages to find the team's base, where he reports the Dominators' activity. The two beings have set up drilling sites around the island, and their next move is to examine the Dulcians and determine if they would make suitable slave labor.

The Doctor and Jamie are taken captive on the Dominators' ship, while Cully and Zoe travel to the capital to try to convince the Dulcian council of the threat. But the pacifistic Dulcians prefer to debate or do nothing rather than take action, and they find Cully's claims hard to believe. Without the support of the planetary council, only the Doctor, Jamie and Zoe can help the Dulcians to find out what the Dominators want with their planet.