Bart has a "graphic" novel idea and pursues his lifelong dream of owning a comic book store, much to the dismay of the Comic Book Guy. Meanwhile across town, the Springfield Retirement Castle is on the brink of collapse. If it closes for good, where's Grampa to go? Then back on the homefront Marge puts her sharply-honed household know-how to work to solve a mystery. Simmer this summer with the Simpsons!