A momentous historical occasion arrives at Twilight's doorstep: The missing Griffon Sun Opal has been discovered! Celestia plans to return the gem to the rightful owners, the griffon kings and tasks Twilight to organize a gala in their honor. Everything seems be running smoothly until disaster strikes: The jewel is stolen! Twilight will find an unlikely ally to unravel the mystery of the theft.

The story is a re-imagining of Agatha Christie's “The Jewel Robbery at the Grand Metropolitan”
In canon with MayorofEquestria's "Trottin' On Sunshine".
Many, many thanks to the fantastic Missangest for that gorgeous cover image!