Stitch is scared about having an injection in his bum, so he and Mo are transported back to 1351 Italy where the Bubonic Plague is spreading like wildfire and everyone's scrambling to find a cure.
After injuring his rear end, Stitch is afraid to go to the school nurse for a tetanus shot. However, a visit to Italy during the Black Plague and a dose of primitive medical procedures lead Stitch to overcome his fear in the interest of preserving his health and his hide.