Rachel Corn and the Loch Ness Mess, Corn Productions, at the Cornservatory. Playwright Becky Werve surely didn’t intend her title to be so apt. “Mess” is the word for her poorly plotted fourth musical mystery for children, which places the Corn kids in familiar supposedly scary or silly scenarios. This time they’re sleuthing in Scotland, but the bickering sibs haven’t changed at all. Rachel is still a nosy know-it-all who bullies her goofy, awkward, timid younger brother (Chris Jacobs in a welcome reprise of the role). In just 50 minutes they look for a missing heirloom diamond, get scared by ghosts, explore Loch Ness, seek out fairies, discover the fate of a lost uncle, endure a spirited seance, and…well, you get the picture.

Clearly the show is crammed with whatever enchanted Werve on a recent trip to Scotland, but her sampling of Scottish people, stories, and traditions isn’t as delightful for the audience. The Corn crew has done almost everything here before and done it much better. The only bright moment is a spoof of a J. Lo video in which the Corn family sing and shake their booties to “Bobby From the Block.” One hilarious song-and-dance number, however, can’t save this show: the actors stumble over lines and often garble their accents, the staging is confused (Werve also directs), and the slapdash story lacks excitement for kids and credibility for adults.