Bob, Scoop and Muck are to carry out repair work at Littletown Tunnel, including relaying bricks on the inside wall. Bobsville's mains electricity is being stopped before work in the tunnel can commence, requiring Bob to power temporary lighting using the Electric Generator. Lofty is sent to Farmer Pickles' farm in order to clear some logs. Scoop is hitched up to the Generator and leaves with Bob and Muck to the tunnel, while Lofty takes the turn to Farmer Pickles' farm. Bob then proceeds to check the work schedule, which starts off saying Muck is to enter the tunnel with the bricks. At first, Muck answers without hesitation and gets to the entrance, but the internal darkness deters him/her from going in, making him/her stop immediately. Bob starts up the Generator to supply power to the temporary lighting, in hopes of illuminating the tunnel brightly enough. Meanwhile, Lofty arrives at the farm and is greeted by Travis, who is going to transport the logs to Farmer Pickles' Barn. Lofty starts loading the logs into the trailer.
In the Building Yard office, Wendy is happy to have some "peace and quiet", but is suddenly alarmed by a loud noise coming from inside Bob's house. Pilchard has turned on the television set and is watching what appears to be a sports broadcast. Wendy turns off the TV set and gets Pilchard going out. Back at Littletown Tunnel, Scoop jokingly teases Muck by singing a derogatory song, but Muck, despite shaking in fear, swiftly charges into the tunnel and makes it in, only to be unsettled when the Generator struggles to keep powering the lights for a split second. At the Building Yard, Pilchard is greeted by Dizzy, who takes her inside her mixer drum to go see what Lofty is doing. Muck has just made it to the missing part of the wall, but she attempts to encourage herself not to let the darkness distract from the mission and manages to lay the bricks in place. Bob asks Scoop to supervise the Generator, while he walks in to start laying the bricks. Just as Muck tries to rush back out of the tunnel, the Generator malfunctions and shuts off, which causes the lighting system to go out as well. Bob notices this and sees Muck shivering in terror, asking to turn the lights back on quickly.
Pilchard and Dizzy arrive at the farm while Lofty is still loading logs. Dizzy, who shows up from behind Lofty, inadvertently gives him a fright for a second before he can pay attention to them. Back at the tunnel, Scoop asks Bob if he thinks Muck will be alright, only for Bob to realize that Muck has a fear of darkness. Bob walks back into the tunnel with a torch (flashlight) and tells Muck there is no point staying inside, instructing him/her to follow Bob's torch. However, the darkness in the tunnel makes Muck act paralyzed. This makes Bob believe that Muck is literally stuck inside the tunnel, and he goes to tell Scoop of the situation. Scoop compares this to Lofty's fear of heights (acrophobia), whch gives him an idea. At the farm, Lofty had finished loading the last log onto Travis, while Bob and Scoop arrive and take him with them. Scoop also takes Pilchard inside his rear bucket. Muck is still standing inside the tunnel, albeit slightly more relieved, only to see Lofty coming through the other end, which startles him/her before realizing it is him. Muck tells Lofty he/she is afraid of the dark, to which Lofty responds by comparing it to his fear of heights and trying to calm Muck down by telling him/her that "everyone's afraid of 'something'" and to follow him out. Despite Lofty's encouragement, Muck is still unable to move an inch because of his/her fear. Lofty then goes out to inform Bob that Muck really is too scared to move and is in deed stuck. At the Building Yard, Wendy goes out looking for Pilchard with a bowl of cat food and asks Roley if he knows where Pilchard could be, to which he responds by saying she may have gone to visit Lofty.
While Bob, Scoop and Lofty are discussing ways to get Muck out of the tunnel, Pilchard sneaks into the tunnel without the others knowing. Seeing Muck and his/her shadow in the dark gives Pilchard a fright and she snarls in terror. Muck, however, does not recognize her and mistakes her for a ghost. This manages to make Muck charge out of the tunnel at full speed, and he/she ends up shoving Bob while emerging from behind him. That night in the Yard, Muck tells Roley about the supposed "ghost" in the tunnel (Pilchard), describing his/her interpretation of the events. Muck then denies the fact he/she was scared, but does not hesitate to mention getting out fast.
Muck is revealed to be achluophobic (afraid of the dark).
This is the first episode in which Travis appears, but not Spud.
Stock footage from this episode is used in the credits of the Original Series.
This is the first episode to feature the Generator. Scoop is also shown to be able to tow it.
Voice samples from this episode ("Can we Fix It?", "Yes, We Can!" and "Uh, yeah, I think so") were later recycled for Buffalo Bob (Season 1), albeit sped up and with only Muck saying "Yes, We Can!". The sped up variants of said voice samples (not including Lofty's) were also used for the Scoop and Roley kiddie rides by Jolly Roger.
This episode was the first ever Muck dedicated episode.
Muck leaves the Building Yard without bricks in the front blade, but they appear when he/she is en route, right before arriving at the tunnel. Also Lofty has his sad face in that scene.
When Bob, Scoop, Muck and Lofty leave the yard at the beginning of the episode, they turn left and then right at the first T junction, but instantly in the next scene, they are coming in from behind the yard.
When Bob starts up the Generator to activate the lights, it does not appear to be connected, yet a cable appears after several scenes.
Lofty manages to pick up the logs, even though they appear to be too big for his hook.
When Wendy covers her ears after hearing the noise from the television set, her hands do not reach.
In the UK dub when Lofty enters the tunnel to see Muck, Lofty's voice sounds different and much similar to Bob's voice.
(Pilchard had just came through the tunnel, and suddenly sees Muck's shadow and snarls in panic)
Muck: (screams) GHOSTS!! (runs out screaming, and Pilchard jumps out of the way. Muck then emerges out and shoves Bob with his/her front blade)
Bob: Well, I'll be blowed! I thought you were stuck in there for good!
Muck: Oh.. Me too.. Bob! There's ghosts down there! Horrible, wailing ghosts!