The Scorpion's Tale

After a field trip to the desert, Lisa discovers that the desert water mysteriously makes typically combative creatures get along, so she brings some of the water home as a souvenir.<br> When Grampa moves in with the family after getting kicked out of the retirement home, Homer secretly tests the desert water on Grampa, who is instantly cured of his crankiness.<br> <br> A pharmaceutical representative (guest voice Herzog) gets word of Homer’s discovery and quickly tries to replicate the water into a drug, using Grampa as the primary guinea pig.<br> But when the pills get in the wrong hands and are sold on the black market, unexpected side effects of the new drug take an eye-popping toll on the elderly citizens of Springfield, and the Simpsons learn that their new medical cure comes with major consequences.