Young, brazen, beautiful, and unapologetically brilliant, Margaret Fuller accepts an invitation from Ralph Waldo Emerson, the celebrated Sage of Concord, to meet his coterie of enlightened friends. There she becomes “the radiant genius and fiery heart” of the Transcendentalists, a role model to a young Louisa May Alcott, an inspiration for Nathaniel Hawthorne’s Hester Prynne and the scandalous Scarlet Letter, a friend to Henry David Thoreau as he ventures out to Walden Pond . . . and a muse to Emerson. But Margaret craves more than poetry and interpersonal drama, and her restless soul needs new challenges and adventures.

And so she charts a singular course against a backdrop of dizzying historical drama: From Boston, where she hosts a salon for students like Elizabeth Cady Stanton; to the...

Young, brazen, beautiful, and unapologetically brilliant, Margaret Fuller accepts an invitation from Ralph Waldo Emerson, the celebrated Sage of Concord, to meet his coterie of enlightened friends. There she becomes “the radiant genius and fiery heart” of the Transcendentalists, a role model to a young Louisa May Alcott, an inspiration for Nathaniel Hawthorne’s Hester Prynne and the scandalous Scarlet Letter, a friend to Henry David Thoreau as he ventures out to Walden Pond . . . and a muse to Emerson. But Margaret craves more than poetry and interpersonal drama, and her restless soul needs new challenges and adventures.

And so she charts a singular course against a backdrop of dizzying historical drama: From Boston, where she hosts a salon for students like Elizabeth Cady Stanton; to the...