The Doctor - Matt Smith
Clara - Jenna-Louise Coleman

Captain Zhukov - Liam Cunningham
Professor Grisenko - David Warner
Lieutenant Stepashin - Tobias Menzies
Piotr - Josh O' Connor
Onegin - James Norton
Belevich - Charlie Anson
Skaldak - Spencer Wilding
Voice Of Skaldak - Nicholas Briggs

Stunt Coordinator - Crispin Layfield
Stunt Performers - David Newton, Marcus Shakesheff, Tom Aitken

First Assistant Director - Ken Cumberland
Second Assistant Director - James DeHaviland
Third Assistant Director - Heddi-Joy Taylor-Welch
Assistant Director - Daneille Richards
Location Manager - Nicky James
Location Assistant - Iestyn Hampson-Jones
Production Coordinator - Gabriella Ricci
Production Secretary - Sandra Cosfeld
Production Assistants - Rachel Vipond, Samantha Price
Asst. Production Accountants - Rhys Evans, Justine Wooff
Assistant Script Editor - John Phillips
Script Supervisor - Steve Walker
Camera Operator - Joe Russell
Focus Pullers - James Scott, Julius Ogden
Grip - Gary Norman
Camera Assistants - Meg De Koning, Sam Smithard, Evelina Norgren
Assistant Grip - Owen Charnley
Sound Maintenance Engineers - Ross Adams, Chris Goding
Gaffer - Mark Hutchings
Best Boy - Stephen Slocombe
Electricians - Bob Fernandes, Bob Milton, Gafin Riley, Gareth Sheldon
Supervising Art Director - Paul Spriggs
Set Decorator - Adrian Anscombe
Production Buyers - Adrian Greenwood, Holly Thurman
Art Directors - Amy Pickwoad, Carly Reddin
Standby Art Director - Nandie Narishkin
Assistant Art Director - Richard Hardy
Art Department Coordinator - Donna Shakesheff
Prop Master - Paul Smith
Prop Chargehand - Ian Griffin
Set Dresser - Jayne Davies
Prophand - Austin J. Curtis
Standby Props - Garry Dawson, Helen Atherton
Dressing Props - Mike Elkins, Paul Barnett, Rob Brandon
Graphic Designer - Chris Lees
Graphic Artist - Christina Tom
Storyboard Artist - Andrew Wildman
Petty Cash Buyer - Florence Tasker
Standby Carpenter - Will Pope
Standby Rigger - Bryan Griffiths
Practical Electricial - Christian Davies
Props Makers - Penny Howarth, Alan Hardy
Props Driver - Gareth Fox
Construction Manager - Terry Horle
Construction Chargehand - Dean Tucker
Scenic Artist - John Pinkerton
Assistant Costume Designer - Fraser Purfit
Costume Supervisor - Carly Griffith
Costume Assistants - Katarina Cappellazzi, Gemma Evans
Make-Up Artists - Sara Angharad, Vivienne Simpson, Allison Sing
Casting Associate - Alice Purser
Assistant Editor - Becky Trotman
VFX Editor - Joel Skinner
Dubbing Mixer - Tim Ricketts
ADR Editor - Matthew Cox
Dialogue Editor - Darran Clement
Sound Effects Editor - Paul Jefferies
Foley Editor - Jamie Talbutt
Graphics - Peter Anderson Studio
Additional Visual Effects - BBC Wales Visual Effects
Online Editor - Geraint Pari Huws
Colourist - Mick Vincent

Ice Warriors Created By
Brian Hayles

With thanks to
The BBC National Orchestra of Wales
Conducted and orchestrated by Ben Foster
Mixed by Jake Jackson
Recorded by Gerry O' Riordan

Original Theme Music - Ron Grainer
Casting Director - Andy Pryor CDG
Production Executive - Julie Scott
Post Production Supervisor - Nerys Davies
Production Accountant - Jeff Dunn
Sound Recordist - Deian Llyr Humphreys
Costume Designer - Howard Burden
Make-Up Designer - Barbara Southcott
Music - Murray Gold
Visual Effects - The Mill
Special Effects - Real SFX
Prosthetics - Millennium FX
Editor - William Oswald
Production Designer - Michael Pickwoad
Director of Photography - Suzie Lavelle
Script Producer - Denise Paul
Line Producer - Phillipa Cole

Executive Producers - Steven Moffat, Caroline Skinner

The Doctor and Clara land on a damaged Russian Submarine in 1983 as it spirals out of control into the ocean depths.

An alien creature is loose on board, having escaped from a block of Arctic ice. With tempers flaring and a cargo of nuclear weapons on board, it’s not just the crew but the whole of humanity at stake!

It is the North Pole, in the year 1983. Aboard a Russian submarine, a warning repeats that the "signal is genuine." The Captain and first mate use their keys to prime an ICBM launch. They prepare to fire, but are interrupted by the entrance of the Professor, singing. The Captain reports the drill has been abandoned. The first mate says they must run it again, to which the Captain says, "Tomorrow." The Captain then asks the Professor about the "specimen," wondering if it's a mammoth. In the hold, the crewman in charge of the specimen muses that they are supposed to wait till the crew arrives back in Moscow to thaw the specimen out. However, he uses a blowtorch to thaw the block of ice, until he is grabbed by a claw that emerges from the ice.

Havoc erupts on the submarine, the hull has been breached and crew members are being attacked by a green armoured figure. The TARDIS materialises as the Captain orders the sub to be brought to the surface, The Doctor and Clara are thrown across the bridge and Clara concludes that they are not in Las Vegas, as they expected to be. The Captain asks who they are, while being informed by a crew member that the main turbines aren't responding. The Doctor tells them their only chance to survive is to use the lateral thrusters in order to land on a ridge which will preventing it from dropping further, which the captain then orders the crew to do.

Crew members search the Doctor and Clara, confiscating a number of items from his pockets, including a doll, a ball of yarn and his Sonic Screwdriver, and the TARDIS dematerialises. Clara falls into a puddle after a jolt rocks the sub, temporarily losing consciousness, and wakes up to the Doctor and the Captain arguing. They are interrupted by a raspy noise coming from behind the Doctor, who initially thinks that it's gas, but turns around to find the green armoured figure, which he recognises as an Ice Warrior, who identifies himself as Grand Marshal Skaldak. The professor reveals that Skaldak has likely been sleeping under the ice for five thousand years. Just as the Doctor seems to be close to diffusing the tense situation, Lieutenant Stepashin sneaks up behind Skaldak and electrocutes him with a cattle prod. The Doctor berates the Lieutenant and reveals that it was an extremely bad idea to have done so, and warns the crew to lock up Skaldak.

They chain Skaldak up, and he asks one of the crew if he has been asleep for 5,000 years. The crewman confirms it. Meanwhile, the Doctor tells the Captain and Clara that Skaldak is so feared that his enemies would carve his name into their flesh. The Captain wants to know more, and the Doctor says that there isn't time, before telling him more.

Skaldak signals for his brothers to save him. Back with the Captain, the Professor, the First Mate, and the Doctor, Clara says that she wouldn't make a very good spy as she doesn't speak Russian. The Doctor tries to shush her. Stepashin believes that Skaldak is a Western plot.