The night before her doctor's appointment, five year old Sofia worries about the shot she knows she'll have to get. As she drifts off to sleep, Sofia finds herself on an adventure with her trusted guide Mr. Whiskers, who is eager to teach her the history and purpose of vaccines. The pair sail across the ocean learning important lessons about vaccines at each stop they make. By the end of their adventure, Sofia realizes the importance of getting vaccinated, and the next day she goes to the doctor's office prepared to get her shot.