Tell you which feature the "Mane 6" acting as detectives. the original book?

They formed a secret alliance to prevent "snacking sabotage" at future competitions.

Mulia Mild eventually shared her secret recipe for Chocolate Mousse as a peace offering to the Cakes. The Missing Evidence

A single, neon-blue feather was found near the dessert carriage. It didn't belong to any of the suspects.

Twilight Sparkle once revealed that the hardest part of the "MMMystery on the Friendship Express" wasn't actually finding the culprit—it was the paperwork she had to file with the Equestria Rail Authority afterward.

According to behind-the-scenes Equestrian lore, here is the "untold" side of that sugary crime: The Secret Security Detail

Princess Celestia reportedly ate a "consolation cupcake" in her cabin while the investigation was ongoing. The "Baker’s Pact"