The Doctor along with his companions gate-crash N.A.S.A.'s control room as it awaits a message from a Mars probe. When the signal eventually arrives, the message says 'God Save The Queen' written in stone to everyones amazement. The Doctor determines that the message was written in 1881.
The Doctor travels with Bill Potts and Nardole to an underground cavern on Mars in 1881 and its not long before the Doctor comes across an Ice Warrior who an English soldier has called Friday after the character in Robinson Crusoe. Nardole is sent back to Tardis and accidentally sends the space ship back to the University where the Doctor has been hiding out.
A battalion of English troops have been transported here to mine precious stones using a laser provided by Friday. Eventually they break into a large room with a golden sarcophagus in it. The Doctor realises that the sarcophagus is that of an Ice Warrior and warns everyone to leave.
One of the soldiers visits the Sarcophagus on his own and starts to steal the gems. In stealing the gems, he inadvertently wakes up the Ice Warrior Empress.
When the Empress wakes up, the soldiers storm the room and there's a stand off. The Doctor tries to mediate between the two groups. Friday reveals that the Ice Warriors have been asleep for 5,000 years and Mars is no longer inhabited and that they require help to move to another planet. The Empress asks Bill Potts for advice as she's the only other female in the room which shocks Bill but she sides with the Doctor.
One of the British soldiers twitches and accidentally shoots the Empress but the bullet rebounds off the thick suit. The Empress starts to shoot at the British soldiers as they retreat. One of the British Soldiers, Godsacre uses the laser gun to block the route of the oncoming Ice Warriors.
Godsacre takes control of the battalion as he reveals that the Colonel was a coward and they tried to hang him for cowardice but he some survived. The Doctor, Bill Potts and the Colonel are put in a cell.
Ice Warriors begin to come up out of the floor and start attacking the troops. Friday comes up through the ground in the Doctor's cell and helps them escape.
The Doctor confronts the Empress and threatens to use the laser to defrost the ice at the Martian north pole which will flood the chambers and freeze everyone. The Captain of the battalion appears and holds a machete at the Empresses neck calling a halt. The Captain makes his escape but is shot and killed by the Colonel he had deposed. The Colonel pledges his allegiance to the Empress who accepts it.
The Doctor sends out a transmission on behalf of the Ice Warriors looking for a new planet and help to get to. The message is received by the Alpha Centauri who plan to come and help.
Nardole had sought help from The Master to get back to Mars. When the Tardis arrives, the doctor is not pleased to see that Missy is onboard the Tardis.