Sapphire and Steel

When Robert's parents suddenly vanish, a pair of strange time-traveling agents named Sapphire and Steel arrive and inform Rob that they are his only hope in getting his parents back.

Sapphire and Steel determine that Helen's bedroom is the location of the time break. Rob begins to distrust the mysterious agents and sees a chance for escape when a policeman finally arrives.

Sapphire and Steel investigate the upstairs hallway after Rob sees a pair of ghostly soldiers on the landing. A living pool of light has escaped from Helen's room and now lies in wait in a portrait.

Steel's drastic measures to save Sapphire and trap the pool of light prove effective. Sapphire places the pool of light in a freezer to keep it from escaping again and tends to Steel's recovery.

The time break strengthens after a nursery rhyme hidden in a book becomes stuck in Helen's head. Sapphire burns the book and Steel and Lead barely succeed in stopping the time break from spreading.

Lured by a vision of his father, Rob walks into a trap in the basement. A pool of light has taken him back in time to the 1700s when the house was first being built.

For their new assignment, Sapphire and Steel arrive at an abandoned railway station haunted by supernatural figures.

Sapphire and Steel discover the ghost is a young World War I soldier who died in battle. They begin to suspect the railway station might be a recruitment ground for the dead.

After Sapphire narrowly saves Steel from meeting the same fate as the doomed fighter pilot, Steel becomes determined to figure out why the ghosts are being recruited at the station.

Steel continues to taunt the ghost of the solider but pauses when he finds Sapphire and Tully unconscious. A hallway in the railway station has become a re-creation of a submarine where the men died.

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.

With Sapphire unconscious, Steel is unnerved by the appearance of her ghost on the railway platform. Steel has a chat with her ghost to determine if she is real or a trick perpetrated by the darkness.

Sapphire and Steel awake to find they have been shunted forward in time by twelve days. In that time, the darkness has gone and so have all the ghosts.

Sapphire succeeds in making contact with the darkness at a great personal risk. Steel negotiates with it by promising a powerful source of resentment in exchange for a return to present day.