This story is a sequel to Wolf at the Door
In the aftermath of the Bad Wolf seizing control over the 9th Doctor's body, The Doctor's past self and everypony else involved with the incident in the matrix must look for a way to free the Doctor from the Wolf's corruptive power.
Meanwhile, the Wolf has been busy wreaking haphazard vigilante justice across the galaxy, and now threatens to bring the battle to the home front as Equestria enters the 21st Century.