In the third episode of the four-part story "Warriors of the Deep," the Doctor (Peter Davison) and his companions are stranded on a 21st century nuclear sea base, which is about to be besieged by the dreaded Sea Devils and Silurians. This time, the combined villains intend to destroy all mankind with the help of a new henchman: an electrically charged sea beast called the Myrka. Originally telecast January 12, 1984, "Warriors of the Deep, Episode 3" was written by Johnny Byrne. ~ Hal Erickson, All Movie Guide