Patti Smith is the author and narrator of M Train. The memoir focuses primarily on Smith’s life between 2011 and 2013, with many flashbacks to earlier times. Smith is an accomplished writer, photographer, musician, and artist, but the scope of her career is not the focus of this memoir. She refers only occasionally to going on tour. She is sometimes invited to photograph the belongings of historical figures or give talks and interviews, and she mentions her friendships with the Beat poets. Despite these references, Smith avoids discussing her fame in her memoir, instead describing a solitary and often quiet life. She navigates moments of Solitude and Connection as a fiercely private person negotiating her interactions with other people. She lives alone in an apartment in Greenwich Village, writing in cafés and remembering her marriage to her husband, who died in 1994. Smith has two children, though she only mentions them a few times, and they do not appear in the present-day narrative. She spends many holidays in solitude and seems to prefer her own company.

Smith is a very introspective figure. She develops strong connections to books, television shows, and inanimate objects, but she mostly keeps those connections to herself.