The Doctor and Clara find themselves dealing with Cold War tensions when
the TARDIS lands aboard a disabled Soviet ballistic submarine. The
Doctor isn't the only alien being on board however - while engaged in
undersea drilling, Professor Grisenko thought he'd found a mammoth and
brought the creature on the boat encased in ice. It isn't a mammoth but
an Ice Warrior, who has been lying dormant for 5000 years. He identifies
himself as Grand Marshal Skaldak but when he cannot contact others of
his kind, he assumes he is the last of his race. He now has every
intention of...
