New York City, 1957. Lionel Essrog, a private detective living with Tourette syndrome, tries to solve the murder of his mentor and best friend, armed only with vague clues and the strength of his obsessive mind.

A Black musician, now in the later stages of his life, harks back to the magical moments in his childhood, career, and his relationship with his father who introduced him to his first true love: his trumpet named Betty.