I t is predawn in Macon, Georgia, and at 4 o’clock on this December morning, in 1848, the city does not move. But the Ocmulgee River flows along the eastern shore, and so, too, an enslaved couple moves, ready to transform, in a cabin in the shadow of a tall, white mansion. They have scarcely slept these past few nights, as they rehearsed the moves they now perform.

Ellen removes her gown, forgoing a corset for once, though she needs to flatten or bind the swell of her breasts. She pulls on a white shirt with a long vest and loose coat, slim-legged pants, and a handsome cloak to cover it all. Advertisement She dresses by candlelight.

All around are the tools of her trade as a seamstress — workbaskets stocked with needles and thread, pins, scissors, cloth. Her husband’s handiwork is in evidence as well: wood furniture, including a chest of drawers, now unlocked. Ellen slips her feet into gentleman’s boots, thick-soled and solid.

Though she has practiced, they must feel strange, an inch of leaden weight pulling each sole to the ground, an extra inch she needs. Ellen may have inherited her father’s pale complexion, but not his height. Even for a woman, she is small.

William towers beside her, casting long shadows as he moves. They must do something with her hair, which he has just cut — gather it up, pack it. To leave it behind would be to leave a clue.

There are the final touches: a silky black cravat, also the bandages. Ellen wears one around her chin, another aroun.