This Radiolab episode, part of a shark-themed week, explores the potential of shark antibodies in fighting cancer. Scientists are studying shark blood, seeking a "molecular superhero" with unique properties. These small, flexible antibodies can access tumor areas inaccessible to human antibodies. The episode delves into the evolutionary origins of these shark antibodies, tracing them back 500 million years. The story then transitions to modern labs where sharks are being studied for their healing potential. The program raises the question of whether these creatures we often fear could actually hold the key to curing disease. The episode features interviews with various scientists and researchers involved in this research. Becca Bressler reported and produced the episode with Matt Kielty, who also contributed original music. The episode also includes sound design, fact-checking, and editing by a team of contributors. Listeners are encouraged to sign up for the Radiolab newsletter and support the show through membership. Radiolab's science programming is funded by several foundations, including the Gordon and Betty Moore Foundation.