Beings from the past that are like Sapphire and Steel but working for a higher power are revealed and the trap is sprung, a deception is underway but for who?

Trapped Sapphire and Steel must use their wits and the help of the tenant to escape their prison and trap the faceless man and keep him from causing more harm.

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. The appearance of a second ghost and the discovery of a recording with the last words of three dying submariners all but confirm their suspicions. The investigation becomes even more difficult and dangerous when the ghost of a fighter pilot forces Steel to experience a deadly plane crash.

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.

The missing shop owner and missing former roommate of the tenant are found in an unexpected place. Sapphire tries to contact the missing roommate. The faceless man intervenes.

Who is the new Landlord? He confronts Sapphire and Steel but his face is not what it seems. He warns them to leave or suffer the same fate as the missing shop owner.

Who is the mysterious Johnny Jack from 1957 and what is his connection to the man from 1925 and the man from 1948? The woman from 1948 wants to talk to Sapphire, Steel and Silver. Silver reveals that they are trapped.

An encounter with a man from 1925 causes Sapphire, Steel and Silver to question why they are in this place. Time shifts forwards 20 minutes and footsteps are heard outside. Steel goes out to investigate. A stranger arrives.

Sapphire and Steel investigate strange happenings at a pawn shop. Children from the past are appearing, but how are these children connected to old photographs? What does the single tenant in the upstairs room know?

Sapphire and Steel receive a puzzling assignment at an apartment complex where time is poised to attack. However, their inspection of every room in the complex reveals nothing suspicious. Even the abandoned top floor reveals no indications of trouble. It is only after investigating the roof that Sapphire and Steel discover an invisible time-capsule from 1500 years in the future. A couple and their new baby are living inside the capsule as an experiment, but they are in grave danger because of a horrible figure hidden inside the capsule with them.

The time break strengthens after a nursery rhyme hidden in a book becomes stuck in Helen's head. Sapphire burns the nursery rhyme book and Steel and Lead barely succeed in stopping the time break from spreading. The kitchen is left a windblown mess and Helen and Rob help Sapphire with the clean-up effort while Lead and Steel keep watch upstairs. Everything takes a turn for the worse when two more pools of light escape from the bedroom and Rob suddenly goes missing.

On an ordinary evening, a mother and father sing nursery rhymes to their daughter Helen before bed. Their teenage son Robert becomes alarmed when all the clocks in the house stop working. He hurries upstairs to find that his parents have vanished. Left alone with Helen and no neighbors nearby, Rob calls the police for help. But a pair of strange, time-traveling agents named Sapphire and Steel arrive instead and inform Rob that they are his only hope in getting his parents back.

After Sapphire disappears while trying to contact the creature inside the capsule, Steel must figure out where she has gone and how to proceed with the investigation. Luckily, technology specialist Silver arrives to lend a hand with getting inside the capsule. Rothwyn and Eldred discover their child has gone missing and are at a loss for what to do next. Meanwhile, their adult-sized infant wanders the capsule under the control of the creature hidden inside the wall.

Steel's drastic measures to save Sapphire and trap the pool of light prove effective, if extremely dangerous. Sapphire places the pool of light in a freezer to keep it from escaping again and tends to Steel's recovery. She also enlists Rob and Helen's help in removing all the objects in the house that could become hiding places for other pools of light. Sapphire and Steel welcome the arrival of fellow agent Lead, a gentle giant with a huge personality to match his huge stature.

Sapphire and Steel subdue the changeling and find where the time source is hiding in the wall. Without their technician, however, they have no way to deconstruct the wall and defeat the creature hidden inside. Steel's decision to resort to drastic measures pays off when the couple reappear in the capsule and the changeling becomes an infant again. But the creature inside the wall still thrives and presents a larger threat than anyone could have imagined.

Sapphire and Steel awake to find they have been shunted forward in time twelve days. In that time, the darkness has gone and so have all the ghosts with it. A frightened Tully tries to convince Sapphire and Steel that he needs to leave the station for personal reasons, but they can guess he wants to leave because he made a deal with the darkness. While Tully's bargain failed, Sapphire reluctantly agrees to make contact with the darkness so that Steel can make his own deal with the enemy.

Once Silver concocts a way inside the capsule, he transports Sapphire and Steel into the experimental pod from the future. The couple are no where to be found but Sapphire, Steel, and Silver come face-to-face with the adult-sized infant. Sapphire deciphers that the overgrown baby is a changeling controlled by time. The changeling senses that the three time agents are a threat and the force controlling the changeling commands that he destroy them.

After Silver's return, the three time agents question the couple from the future about their origins and their knowledge about the machine that transported them through time. The couple reveals some horrifying information about the future that directly relates to the creature inside the wall. Now with an understanding of the creature's motivation, Sapphire and Steel must prevent the creature's escape and manipulate time in order to save all of humanity.

Two of the party guests are dead. Who will be next? This is no traditional murder mystery, and Sapphire and Steel cannot agree on who would have a motive to commit this crime.

Sapphire and Steel investigate the upstairs hallway after Rob sees a pair of ghostly soldiers on the landing. Unbeknownst to them, a living pool of light has escaped from Helen's room and now lies in wait in a portrait at the top of the stairs. Sapphire walks right into the trap and disappears from the house. Only faintly able to communicate with Steel and Rob, Sapphire tells them she is stuck in a freezing cottage with the sensation that something sinister is there with her. Steel and Rob discover that Sapphire is trapped in the portrait and must work quickly to avoid losing her.