Something deadly is roaming the tunnels of Janus VI, damaging equipment and killing men. The Enterprise responds to a distress signal from the mining colony and Kirk, Spock and McCoy plunge into a bizarre adventure as they race against time to save human lives, the colony - and something they did not expect to find. Aware of his peril, Spock moves alone through uncharted areas of the soul in order to discover the truth of the Devil in the Dark. Complete episode told with 300 colour photographs.