Something has been taken from The Doctor. His Memories are Broken. Witness The Past and The Present in two connected Adventures as The Doctor meets his New Companion.
When The Doctor first met Lily Richardson they encountered Mysterium. Once again The Doctor faced Mysterium on a Clifftop. The Doctor and Nathan face him yet again. The darkest chapter in 'The Silver Doctor' is here.
Mysterium Returns. Secrets are Revealed. The Future hangs in the Balance. The Doctor is about to learn that his Future is closer than he thought. The Final Chapter in this story arrives.