While the main body of expedition has carried onwards (or downwards) into newer, deeper worlds, co-operation between the locals of this level and humanity continue.
A two-person team (and their assigned governing intelligence) work with the locals on a project in Canterlot. One of the humans absolutely loves getting to work with magical horses in a delightful, wonderful world. The other is a huge wet blanket.
The story is about the wet blanket.