Twelve-year-old Iris and her family have moved to Texas. Iris misses her friends and her old home on the coast. She is also now the only Deaf girl at school and finds school life tedious.

Then, in science class, her curiosity is aroused when their teacher tells them about a baleen whale whose unique 55-hertz frequency means he cannot communicate with other whales. Iris is fascinated. Using her passion for old radio equipment, she is determined to try to help the lonely whale, named Blue 55.