These are rapidly becoming guilty pleasures of mine. I can finish them in minutes and they're always good for a couple of laughs. I wouldn't call them mysteries generally...but they are fun.
After traveling to Egypt and India, this volume's setting doesn't seem all that exciting - Scotland. However, the King of Scotland's Sword is missing from the opening ceremony at a museum and they have only a few hours to discover where it is and who stole it. Otherwise, Dash fails! So of course he calls up his cheat code, his cousin Agatha, to solve help him with his case. The Mistery family member they bring along is Granddad Ian, a builder and flier of Hot Air balloons. Not only does he get them there in plenty of time, but he acts as the face of the investigation which allows the kids to search for clues.
Again, there's not much of a mystery here, who-done-it seemed pretty much picked at random. Still, It was fun to read and I already have the next one downloaded.
I wouldn't mind owning a copy of these books, actually. I think they'd be fun to reread.