It’s 1983. The USA and the USSR are in the grip of a second Cold War, while Ultravox and Duran Duran rule the airwaves.
On board a Soviet submarine in the North Pole, Professor Grisenko (David Warner) is bringing back to Moscow what he believes to be a 5000 year-old-mammoth encased in ice. But when the ice melts, an alien creature breaks free and attacks the sub.
When the Doctor and Clara land on board the damaged vessel, the Doctor helps Captain Zhukov (Liam Cunningham) and Lieutenant Stepashin (Tobias Menzies) stabilise the sub’s descent to 700m, then is shocked to discover that the creature is actually Grand Marshal Skaldak, one of the greatest heroes of the Ice Warrior race.
After being knocked out by a cattle prod and chained up in a holding cell, Skaldak sends out a distress sign. When he gets no reply, Skaldak thinks he has been abandoned and has nothing to lose but to use the subs missiles to start a war between the humans. Escaping from his armour, the Ice Warrior kills and dissects Stepashin and two of his officers in a bid to learn how to arm the sub’s nuclear warheads.
The Doctor tries to negotiate with Skaldak by reminding him of his heroic status amongst his race. When that fails, the Doctor threatens to destroy the sub with his sonic screwdriver. Suddenly, a tractor beam takes hold of the sub and lifts it to the surface. Skaldak is then beamed to an Ice Warrior mother ship, but the warheads are still armed. Clara disarms it by singing Duran Duran’s Hungry Like the Wolf.
The episode ends with the Doctor asking the Captain for a lift to the South Pole, where the Tardis has now materialised.