It's been several months since King Sombra was defeated. Since then, Shining Armor and Princess Cadence have been presiding over the Crystal Kingdom, and quite happily so. However, a message arrives one day from Princess Celestia requesting Shining Armor to come back to Canterlot as soon as possible.

On arrival, he was informed of the problem immediately: there've been reports in the castle of a strange being roaming the hallways and bedrooms. Objects and guards have begun to disappear, and there have been sounds coming from the walls. Princess Celestia called upon Shining Armor because of one detail common across all eye-witness reports; even though the only thing anypony ever caught of it was a glimpse, they all reported it to be covered in a familiar form of black chitin...

My first fanfiction, all criticism welcome.