Racing legend Cale Yarborough is working on a secret turbocharger. When the grimy Jethro brothers and slimy Boss Hogg start snooping around, it's up to the Dukes to save Cale's tail.
As a medic for a rodeo, David discovers that an aging cowboy has a serious health condition that could prove fatal; meanwhile, the cowboy's younger brother is mixed up with a gang of cattle thieves.
By permission of Mr. Grace, Mrs. Slocombe moves into a display apartment in Grace Brothers, because her new home is occupied by squatters. Due to a transport strike, Mr. Humphries seeks to join her in her new accommodations.
With Sapphire unconscious, Steel is unnerved by the appearance of her ghost on the railway platform with the other spirits. After Tully agrees to watch over Sapphire's body, Steel has a chat with her ghost to determine if she is real or a trick perpetrated by the darkness. The soldier is not through with trying to get rid of Steel, however, and snares him in barbwire. Meanwhile, the darkness makes a deal with Tully: he can escape the station unharmed if he leaves Sapphire and Steel while they are unconscious and vulnerable.
Governor Gatling wants the staff to join him on his little vacation to a snow cottage. Benson agrees when he learns that Kraus will not attend. Later Kraus changes her mind and Benson has to live with it. He has to live with it harder when the staff gets snowed in.
Ashley Longworth Jr. comes back and asks Erin to be his wife. She has some serious doubts after he says he has lost his faith in God.
Buck masquerades as a convict to break into a prison in an attempt to rescue Jen Burton, who took the blame for a murder her boyfriend, a shipping pirate, really committed. The Earth Defense Directorate believes that she can supply information to put the pirate in jail. Breaking out of the underground prison, Buck and the woman head for a nearby spaceport for return to Earth, but they are pursued by an indestructible android prison guard.
A bookstore owner is infuriated when a strip club opens near his place of business; and man is convinced that he is on the verge of spontaneous combustion.
Real Burt calls Mary, but Alien Burt intercepts Mary on her way to meet him. Jessica confronts Chester with her suspicions that he is cheating again. Eunice tells Corinne that she's fallen out of love with Dutch. Corinne spots Chester with another woman in a restaurant. Billy and Leslie sneak away to a romantic restaurant, only to run into several familiar faces. Tim and Corinne decide to divorce.
Following the devastation at Ringstone Round, Quatermass hears of similar incidents worldwide and returns to London with district commissioner Annie Morgan and a Ringstone 'survivor' Isabel. En route they become separated in a shootout between rival gangs. Meanwhile, the beam of light descends again - near Joe Kapp's home.
Three Bradfords struggle to meet the expectations of others: Nicholas turns truant to escape the long shadow of his siblings; Tom's boss pressures him to participate in a father-son golf tournament; Nancy feels compelled to date a stockbroker uniquely positioned to help David's slumping business.
The Drummond family celebrates the day Arnold and Willis are supposed to be officially adopted until the visit of a ""relative"" leaves their plans in jeopardy. Whitman Mayo guest stars as Jethro Simpson, who sees his way to go from junk to jewels in a last will and testament leaving a fortune to Willis and Arnold.
When a young woman who is supposed to be in prison is found dead at the scene of a robbery, the Angels are called in to investigate. Kris enters prison undercover to find the thieves.
Marion is a star in a community theatre play, and her director/co-star begins to make unwelcome advances toward her.
With Sapphire as a medium, Tully and Steel are able to communicate with the ghost of a woman who was once the soldier's schoolteacher. As they prod the spirit with questions, she reveals that the force helping and controlling the ghosts is a terrible, living darkness. She also gives them the name of the soldier and the details of his untimely death. Satisfied with the information, Tully and Steel finish up the séance but an enveloping darkness creeps through the room and threatens to devour them all.
When a prominent lawyer is murdered, two close friends of the Harts are accused. Jennifer sets out to clear the wife while Jonathan attempts to absolve the husband.
Three old men from Yorkshire who have never grown up face the trials of their fellow town citizens and everyday life and stay young by reminiscing about the days of their youth and attempting feats not common to the elderly.
A beautiful and ambitious young nurse, Harris, who plans to become a doctor when she leaves the Army, finds herself in a misunderstanding with Father Mulcahy. Meanwhile, the camp's water supply is depleted, and the rest of the 4077th is more concerned about where their next shower will come from.