Joe, while on a hiking trip in Spain, decides to check his email at a local cafe. He finds an alarming message from Maggie, the wife of his friend Thomas, urging him to call. Upon calling, he learns the shocking news that Thomas is battling a terminal brain tumor. This comes as a surprise to Joe, as Thomas had appeared perfectly healthy just a few months prior. Overwhelmed with shock and sadness, Joe immediately changes his plans and books a flight back to the US.

During his flight, he strikes up a conversation with his seatmate, Sonia, and shares the news about his critically ill friend. Sonia, curious about their friendship, asks Joe how they met. Joe recounts their unique meeting years ago on a train platform in Chicago. Thomas had approached him with an unusual question, asking if it was a "good museum day morning." This intriguing question piqued Joe's interest and he found himself pondering over it all day.

The following morning, Thomas once again approached Joe on the platform and invited him for breakfast. It was then that Thomas explained his intriguing "museum question." He shared his belief that people are like museums, filled with undiscovered exhibits waiting to be explored. He encouraged Joe to approach strangers with a sense of curiosity, eager to discover what lies within them. This marked the beginning of a deep friendship between Joe and Thomas, with Thomas serving as a mentor to Joe.

Now, years later, Joe is heartbroken to learn about Thomas's terminal illness. He rushes back home, hoping to see his dear friend and mentor one last time.