在1892年的平安夜，大量的雪花提取了人们的意识，并以一个淹死的女家教作为模板，使雪拥有和人类一样的特性，入侵地球，被恐怖威胁的地球需要博士。

而一个年轻家教，克拉拉（S7E01中的天才女孩），当她向博士求助时。博士却在哀悼艾米和罗利，深居简出，坚决不干涉宇宙的问题。

作为老朋友，维多利亚侦探小队。将放纵博士真的放弃人类，或改变他，让他拯救世界，将地球从这个冰冷神秘的而具威胁性的魔爪救出吗？

【超凡智慧间接出现】

The Battle of Demons Run: Two Days Later is a mini-episode that served as a sequel to TV: A Good Man Goes to War and a prequel to The Snowmen. It was first released onto the US iTunes Store and Amazon Instant Video in late March 2013, just prior to the launch of the second part of Series 7, which was 20 months after A Good Man Goes To War and 3 months after The Snowmen. It explained how Strax survived an apparently fatal shot from the Battle of Demons Run, and how he ended up living with Madame Vastra and Jenny Flint in 1888 London.

In the aftermath of the Battle of Demons Run, a battled-scarred Strax lies dead on the floor — or has he just fainted...

Strax is woken up by Madame Vastra and Jenny Flint, and is told that he had not died since they had used alien technology to heal his wounds. Jenny says that he had never truly passed away thanks to the resurrection technology and he had been in a state of unconsciousness for two days while the resurrection device healed him. He's angry about not having died. Vastra and Jenny then announce that the station is being evacuated, and they offer to take Strax with them back to London. Strax is hesitant and at first rudely refuses but then changes his mind and agrees to accompany them.