Phillips and Newman are being transferred when the transfer stops, Kirk asks: "what's wrong?", Swain answers: "A feedback, a bad one", and suggests a solution. A loud voice is heard saying "NO!" and a man leaps from the tower to the floor of the control room. Approaching the image area of the time tunnel he points at Phillips and Newman saying: "Hear me you travellers in time, it is I, Merlin, mightiest of all wizards, at a sign from me you will leave the limbo of time and appear here before me!". The tunnel transfer process begins and Phillips and Newman appear at the transmission point of the Time Tunnel. They are frozen in time like all the other staff. Merlin looking around the Time Tunnel and says: "Welcome........Home!". He then tells them that next time they meet they will do as he wants. Then he sends them to the Cornwell cost in England in 544 A.D.

They meet a young pre-King Arthur while fighting Vikings and on Merlin's behest team up with Arthur. The Vikings apparently kill Doug and capture Tony and Arthur. Tony escapes with Arthur and Doug is rescued by Merlin and Guienvere.

When The Time Tunnel try to recover Newman and Phillips, Merlin reappears. He walks around looking at the electronics and computers saying: "yes, elementary.... simple, predictably simple". Kirk demands to know how he is, and how he got in to the project. Merlin tells them that he is a powerful wizard. Swain replies "We do not believe in magic". Merlin says: "You are living in the very heyday of magic, and you Sir, do not believe! Very well I shall convince you!". Merlin points at Swain and he vanishes, Kirk is some what alarmed and MacGregor is frantic. Merlin points at one of the control stations, Swain reappears, standing on the desk in front of his controls. MacGregor helps Swain down, asking if he is alright. Swain is annoyed and dismissive of MacGregor's fuss. He is far more interested in asking Merlin "How did you do that!", Merlin replies "Magic! simple Magic!". Kirk intervenes, realizing they have no hope against a man how can do with his mind what they do with machines. Merlin now says "Oh yes, my name, it's Merlin!", Kirk says: "King Arthur's magician?!", Merlin says: "That is a position I will hold!" Merlin tells Kirk he needs Newman and Phillips, Kirk orders their transfer. Swain and MacGregor find all the controls  are electrified. Merlin leaves and Kirk orders a maintenance team.

Newman and Arthur are recaptured.. Guinevere is also captured. One of the Vikings kills Arthur. Merlin returns from The Time Tunnel to find Arthur dead, having been killed by a Viking bowman. Merlin unpleased that he must make such a gross intervention. He reverses the arrow's time. Newman and Phillips understand what Merlin has done but not how he did it.

Arthur, Newman and Phillips escape. Phillips gets reinforcements which Merlin disguises as Vikings. With this subterfuge, the Vikings are defeated. Arthur and Newman rescue Guinevere. Arthur and Guinevere are to be married.

Phillips, Newman and Merlin, are watching the wedding, in the time this has taken to play-out, the maintenance team has determined the controls are safe to use. Phillips and Newman are transferred. Merlin just stand there and smiles.