Princess Cadance has been sleepwalking, and has no idea why. Twilight's Advanced Projects group has the perfect way to find out -- assuming Tempest can talk Cadance into going along with it...

In the process, Twilight and her friends learn a few things they didn't know about Cadance's past -- and find some unexpected mysteries as well...

For more of this series, see: Where Trouble Goes.

And also check out the entire series, beginning with Not Exactly Friends.