This story is a sequel to Mission: Improbable

A few weeks after the Spy returned from his extended stay in Equestria, the Medic found that he needed to have a few of those so-called "ponies" to... study. But with robots still attacking Mann Co., how can he find the time to acquire such a specimen?

By sending a scout ahead, of course.

It had been about a month since the changeling incident in Canterlot. Everypony is on edge, because stray changelings keep popping up here and there, trying to blend in with the population. Everyone worries that one of their closest friends, or even their family, could not be who they appear to be. But what happens when a pony isn't really that pony...

...but they're not a changeling, either?