She worries that fire—which she needs desperately for keeping warm—will expose her in hiding, whether by flame or by smoke. At first, she builds a small blaze inside her pot, tindering it with the driest layers of tree bark so as to minimize the smoke. But the idea of making soup in the pot, even if just hot water and some roots, anything to heat her insides, drives her to attempt a small ground fire. In a thicketed area she mounds dead pine branches, dumps the burning embers from the pot on top, and prays the open blaze will go unnoticed. She cleans the pot, adds water and two handfuls of birch root, and sets it upon the fire.

When she walks about, she rolls her feet so as to leave the scantest trace. She forages the forest floor for acorns, mushrooms, and wild garlic, rare to find, beneath the snow, and breaks through the ice blanketing the swamplands to fill her canteen. Weak with hunger, she remains hidden during daylight and moves only at nightfall, after dark.

Róża uses twine to refasten the curling-away soles of Henryk’s boots. Without them, she knows, she will die here in the woods. She darns the holes in her mittens and pulls Natan’s fur hat over her wind-bitten ears, looking skyward to assess the moon. Before setting out, she ties a knot into a length of thread to mark her survival of another day.

Near dawn on her third day in the woods, she eats a meal of boiled birch bark. With no one to save for and scrimp, she devours every last stringy bite. When she burrows down again for another day’s rest, Róża rubs herself warm in a refusal to give in, curl up, and die. She listens for the pulse of music within her: a melody, big and spacious, to carry her outside of her solitary anguish. In the way that other people share the stars—looking up at the exact moment, they see the same night sky—she and Shira have this: The soar of violins mixing with cellos. The flight of notes, like wingbeats, that transport them together, beyond the confines of a forest burrow, a convent wall.

The convent is a winding maze of corridors that Zosia does not yet understand, so she follows the other girls, shivery in their thin starched dresses, as they shuttle from class to chore to chapel. They slow their steps only as they pass by the woodstoves, where they huddle briefly to warm themselves before rushing on. In the children’s quarters, there are just two stoves, one in the community room and one in the corridor outside their bedchamber.