At the last moment, a man rushes out and throws the cover over the pit, saving the Doctor. The man is George Stephenson, who is fascinated by the outlandish metal. He frees the Doctor and they escape with Peri to his workshop, where Luke Ward works.
The Doctor suggests that Stephenson cancel his meeting and he agrees. He dispatches Luke with a message to Ravensworth but the Master intercepts him. He hypnotizes the lad and gives him one of the Rani's control worms. He tells him to make sure the meeting takes place.
The Doctor leaves Stephenson to return to the bath house. On the way, he is again attacked by the Luddites.
The Rani is preparing to leave but the Master persuades her to join with him in taking over the Earth. She kills her two assistants and then set out to take care of the Doctor.
Luke keeps Ravensworth and Stephenson apart to make sure the meeting takes place.
The Doctor and Peri break into the Rani's laboratory again. He finds her TARDIS, but it has been trapped with mustard gas. They survive it by taking gas masks from the Rani's assistants. Within, they find Tyrannosaurus Rex embryos. The Rani's TARDIS launches and the Doctor sends Peri out. It meets up with the Rani in the mine.
Disappointed that her trap has failed to kill the Doctor, the Rani collects a stack of mines. The Doctor follows her and the Master out after sabotaging the Rani's TARDIS.
Peri returns to the pit where she meets the Doctor again.
Luke Ward tells Stephenson that Farraday has been attacked in Red Fern Dell. Stephenson takes his gun and goes to help. When asked about Stephenson by the Doctor, however, Luke claims not to know where he is. The Doctor is suspicious. He finds Stephenson and goes in his place, warning him about Luke.
The Rani lays her mines in Red Fern Dell.
Ravensworth asks Peri to help calm Jack Ward and she identifies a herb that can help. Luke escorts her to Red Fern Dell, where the flower grows. As they approach, the Master aims his TCE. But the Doctor sneaks up and knocks it away, taking the two Time Lords prisoner.
Luke treads on a mine and is transformed into a tree. The Doctor is enraged but the Rani is indifferent. Peri almost steps on a mine but is saved at the last moment by the tree that was Luke. The Doctor forces the Rani to lead Peri to safety.
The Doctor begins marching his enemies back to their TARDIS. But he sees Luddites moving to the dell. He stops the Rani from killing them, gives the TCE to Peri and goes to warn them. But they simply take the Doctor prisoner and tie him to a wooden stake.
At the pit, the Master tries to hypnotize Peri but she has been forewarned by the Doctor. The Rani laughs at this but her laughter degenerates into a coughing fit. She takes a capsule from her wrist but uses it knock Peri out.
Two of the Doctor's captors step on mines, changes into trees. The Doctor is suspended between them but manages to wriggle free without falling onto a mine. He returns to the pit where the Master is waiting.
The Master tries to shoot the Doctor with the TCE but blasts a mine support, causing a collapse. The Doctor and Peri scramble out while the Master and the Rani escape in her TARDIS. But the time vehicle begins to speed out of control. The g-force hurls the two Time Lords to the walls of the vehicle and knocks one of the Tyranosaurs off of its perch. Time spillage causes it to grow to life before the trapped pair.
The Doctor uses the brain fluid picked from the Master's pocket to heal the Luddites and Ravensworth has his men pull the TARDIS up from the depths of the mine. The Doctor and Peri take off, leaving Stephenson to work on his engine.