When Sharon Roseman was five years old, something strange happened. She was playing a game with her friends, and when she took off her blindfold--she didn't know where she was. She was lost on her own block, in her own backyard. For most of her life, Sharon feared it was all in her head, and kept her troubles a secret. Until she saw something on TV that led her to get in touch with Dr. Guiseppe Iaria, who helped her find a diagnosis...and a friend with the same condition. And Sharon's story begs the question--how do we know where we are? What does it take to be able to walk down the hall, or down the block, and back? Jonah Lehrer explains the very recent science that's helping unlock how our brains make maps from moment to moment. Along the way, Karen Jacobsen, who calls herself "the GPS Girl" (her voice can be heard in GPS units in millions of cars around the world), helps Jad and Robert navigate the episode's twists and turns.