The boat slid into the inner marsh, and the walls of green closed behind Mira. She spread her chart on her knees and dipped her pen. But her hand stopped. Water branched into three channels ahead, all the same. No hill rose above the reeds. No rock broke the surface. Every bank looked like the last. Without a fixed point, any line she drew could sit in the wrong place on the map. She paddled to the first channel and marked it. Then she looked back and lost which bend she had come from. The reeds had shifted, or the current had. She scratched out the line. If she guessed, the whole map would fail. A year of work would show a swamp that did not exist. Mira held still and listened. The marsh gave back nothing but frogs and the drip of leaves. Then, under it, she heard singing. A thin voice, high and even, threaded through the reeds. It did not rise or fall. It held one steady note and returned to it, over and over, from a single direction. She turned the boat toward the sound. If the singer stayed in one spot, that spot could anchor her chart. She paddled slow. The channels twisted, but the voice grew clear, and she kept it always ahead. She marked each bend against it now, not against the reeds. The water opened into a still pool. Thick ivy poured down one bank, its wide dark leaves heaped in a green wall. At the foot of the ivy grew a patch of tiny flowers, no bigger than pennies. Their stems bent low over the water. As the wind moved them, they hummed. The bent stems caught the air and sang the one steady note. There was no singer. The flowers made the sound. Mira laughed, quiet and surprised. She reached out and touched a bloom. It swayed and hummed against her finger. The ivy above never moved. The flowers grew only here, in this one pool, from this one bank. She had found her landmark. Not a hill or a rock, but a sound that did not travel. She set the pool at the center of a fresh sheet. She drew the ivy wall and the humming flowers as her fixed point. Then she traced each channel outward from it, measuring by paddle strokes. The lines fell into place. The map held. Mira sat back, her hand steady now. She had the heart of her chart. But as she looked at the three channels spreading from the pool, she understood the cost. The flowers only sang here. Once she paddled out of earshot, her anchor would fall silent behind her. To map the deeper marsh, she would have to leave her one landmark and trust the empty water again.