There are some strange shenanigans transpiring at the New York Museum of Science and History: A recently acquired artifact won't stay assembled, though there's never any signs of a break-in... Raphael joins Mona Lisa to get some answers, but they certainly weren't expecting the culprit to be the museum's mummy! After they accidentally free an evil mutant from his centuries-long imprisonment, Raph and Mona must team up with the misunderstood mummy to save the museum.

Then, the Heroes in a Half-Shell find themselves protecting a vault full of gold when an overconfident millionaire dares criminals to try to get past his latest and greatest security systems! Krang needs the gold for his interdimensional portal, but he's not the only villain in the city with his eye on the golden prize. And what (or who?) is the mysterious final security measure named G.R.E.G.G.?

In the final story, Michelangelo feels overlooked and unappreciated by his family. After stumbling across a magic genie while on his own, he's transported to a dark alternative reality where he never existed: Shredder reigns supreme, and his brothers and Master Splinter are twisted and terrifying versions of themselves! It's up to Michelangelo to overcome his insecurities and realize the importance of his ability to brighten up the world with cheer and fun.

Collects issues #17-20 of Teenage Mutant Ninja Turtles: Saturday Morning Adventures.