Marina Coralwise knew the exact spot where the sunken temple opened to the sea. She had known it for three years, since her mother died with her father's name still locked behind her teeth. Now she crouched on a wet rock, watching the water pull back with the tide, and realized she knew nothing at all. Her mother had described a doorway of black stone. But the sea here stretched flat and gray, and every rock looked the same. She pressed a hand to the light green scales climbing her legs. Her mother had pushed those scales into her skin as a gift, a mark of the mermaid blood in her. The proof of her father waited inside that temple. Her mother had left it there, then told someone where. Marina did not know who. She only had the doorway to find, and the doorway would not show itself. The tide dropped lower. Marina waded out, feeling the cold grip her knees. She ran her fingers along the seabed, hunting for a ledge, a carved edge, anything. Nothing. Just sand and slick stone. She had timed this for the lowest water of the month. If the temple hid here, it should have surfaced. It did not. A bird landed on the rock she had left. Its feathers washed in blue, purple, and green, and its yellow eyes glowed like small lamps. It tilted its head at her, then dipped its tiny beak toward the water. Marina had seen the bird before, always near the shallows, always watching. It hopped, then flew a short way and settled again, farther out than she had searched. She followed, because she had nothing better. The bird led her past a cluster of rocks she had ignored for years. Behind them grew a low bush heavy with orange and red fruit, glowing faintly in the fading light. The bird pecked one loose and let it drop. The fruit rolled off a shelf of stone and vanished into a dark gap below the waterline. Marina knelt and reached into the gap. Her fingers touched a smooth edge, carved and straight. She pulled seaweed away and found black stone, cut by hands, not tides. A doorway. Her mother's doorway. She had searched the wrong rocks for three years, standing paces from the truth. Water still filled the opening. She could not enter now. The tide was rising again, sealing the door. But she had it. She marked the spot in her mind, the bush, the rocks, the gap. Then she stood in the dark water and made herself a promise. At the next low tide, she would go in. The bird watched her from the rock, its yellow eyes steady. Marina looked back at it, then at the fruit bush that had betrayed the door. She knew where the temple lay. Now she needed a way to breathe beneath the sea long enough to reach what her mother had hidden.

Marina came back the next morning to study the door in daylight. The tide was high, the gap sealed, so she could not enter yet. She meant only to watch and wait. But the bird was there again, perched on the wet rock, its yellow eyes fixed on her. It had led her to the doorway. Now it would not leave. She stepped toward it. The bird lifted off, circled once, and settled behind her. She turned. It flew back to the rock, then away again, always returning to the same low shelf near the water. It kept its long feathers spread over that spot like a hand. "You want me somewhere," Marina said. She had followed it once and found the truth. She followed it again. The bird led her along the shore to a cabin she had passed a hundred times. It was pieced from driftwood and ship scraps, its roof heavy with palm leaves. The door hung open. Inside, sand covered the floor, and salt crusted the walls. The bird flew straight to a barrel in the corner and pecked its rusty lid. Marina pried the barrel open. She expected wine. Instead she found a coil of cracked leather tubing, a carved wooden mouthpiece, and a folded note. Her mother's small, slanted hand covered the paper. She read it twice. "For my daughter, who cannot yet breathe below. Your grandmother built this to reach the doorway. The barrel holds air. Sink it, and breathe through the tube." Marina's hands shook. Her mother had planned this. The bird had not guarded a threat. It had guarded a gift, left for the day Marina found the door. She carried the barrel and tubing back to the shore. She fit the mouthpiece to the tube, then pressed the tube through a plug in the barrel's side. She blew air in and sealed it. The barrel held. The bird watched from the cabin roof. Marina looked up at it. "You knew," she said. "You waited for me to find her door first." The tide was rising. She could not test the barrel today. But she had it now, and she understood the bird at last. It had circled her for years because her mother had asked it to. It would lead her nowhere new again. Its work was done. Marina wrapped the leather tube tight around the barrel and sat on the wet rock. The bird lifted from the roof, passed once over her head, and flew out toward the open water. It did not come back. She watched it shrink to a speck and vanish. Then she looked at the barrel in her lap. At the next low tide she would sink it, breathe through the tube, and swim into her mother's doorway. The guide was gone. The way in was hers.

The next low tide came at dawn. Marina carried the barrel down to the water and set it on the wet rock. Then she saw the trouble. Rocks had slid across the doorway in the night. A heap of them now blocked the gap. She pried at the top stones. They shifted, rolled, and settled again, heavier than before. The tide was already turning. She had one hour, maybe less, to clear the passage alone. She could not. "You'll drown doing that." Marina spun. A man stood on the shore behind her. His clothes hung in torn strips. Salt dried white on his chiseled chest. His brown eyes fixed on the barrel, then on her scaled legs, and did not flinch. He was a stranger, washed in from the sea, and he had watched her fight the rocks without offering a hand until now. "Then help me," Marina said. "Caspian," he said. "My ship broke on the reef last night." He looked at the heap. "Those won't move by pulling." He walked past her along the shore. A battered cargo ship sat half-sunk in the shallows, its hull cracked, its rusted hooks and ropes still hanging from broken arms. Caspian waded to it and dragged a coil of rope free. He tied one end to the largest doorway stone. "Now we pull together," he said. They hauled. The stone dragged an inch, then stuck. Marina's hands slipped on the wet rope. The tide crept up her ankles. "It's not enough," she said. "The water's rising." Caspian dropped the rope. He looked at the wreck, then at a small pink lizard sunning on a rock nearby. Its body glowed like a live coal. He grabbed a shard of dry driftwood and pressed it near the lizard. The wood caught a flame. "Fire won't crack stone," Marina said. "No," he said. "But heat and cold do." He wedged the burning wood against the stuck stone. The rock hissed. Then he splashed cold seawater over it. A crack split down the middle. The stone broke in two. They rolled the halves aside. The black doorway showed through, dark and open. Marina's breath caught. Her father had carved that stone. The way in stood clear at last. But the tide was at her knees now. The gap would seal in minutes. "I have to go now," she said. She sank the barrel and gripped the mouthpiece. Caspian caught her wrist. "You don't know what's down there." "I know exactly what's down there," she said. "Proof of who I am." She pulled free and dropped into the black water. The doorway swallowed her. Behind her, on the shore, a stranger she had known for one hour stood guard over a passage that would close before she returned. She had reached her mother's door. Now she was inside it, alone, with a man above who had every reason to be gone when she came back up.

The black water closed over Marina's head. She followed the tube down into the temple, the barrel bobbing above on the surface. Her hands found a stone floor. Ahead, a low chamber opened. Carved shelves lined the walls. On one sat a sealed clay jar, wax still hard around its lid. Her mother's proof. Marina reached for it. Then cold water surged past her knees, then her waist. The tide was rising fast, faster than she planned. The passage behind her was filling. If she stayed to free the jar, the doorway would seal, and she would die down here with it. She grabbed the jar and turned. The passage had shrunk to a black slot. She kicked toward it. Her skirt of palm leaves snagged on a jut of rock. She yanked. The mouthpiece slipped from her lips. Salt water burned into her throat. She clawed for the tube and found only mud. A hand closed around her wrist. Caspian. He had come down after her. He had not waited on the shore. He pushed the mouthpiece back between her teeth and held it there. His other arm hooked her ribs. He pulled. The palm leaves tore free. Together they forced through the narrowing slot as the last stones ground shut behind them. They broke the surface gasping. Marina still had the jar. Caspian dragged her onto the wet rock and dropped beside her, chest heaving. Water ran off his blonde hair. He did not speak. He only stared at the jar in her fist, then at her face. "You went back down," Marina said. "You didn't leave." "I heard you stop moving." He wiped salt from his mouth. "That was reason enough." She should have opened the jar right there. She did not. Her hands shook too hard. Caspian pulled her up and led her along the shore to a cabin pieced from driftwood and ship scraps. Inside, a shelf held fruit and jars of island food. A rough table and chairs stood in the center, lashed from drifted planks. He set her in a chair. He pressed a coconut into her cold hands. "Drink. Then you can look." He crouched close, brown eyes on hers. The space between them held something new. She felt it in her chest, warmer than the cold sea had left her. His hand stayed over hers on the coconut and did not move. "Why do this?" she asked. "You don't know me." "No," he said. "But I want to." Marina held his gaze. Then she set the jar on the table and broke the wax with her thumb. Inside lay a folded scrap of oiled cloth. She unfolded it. A name was written there in her mother's hand. Marina read it and went still. She knew the name. It was not a stranger's. She looked up at Caspian. "I have to find this man," she said. "He's on this island."

Marina tried to stand. Her legs shook and folded. She caught the table's edge and sat back down hard. The name burned in her hand, but her body would not carry her to find the man who owned it. Salt still scorched her throat. Every breath came shallow. If she walked the island now, she would drop somewhere in the brush and find no one. Caspian steadied her shoulder. "You can't search like this. You'll collapse before you reach the trees." "He's here," she said. "I've waited three years." "Then wait one more hour." He crouched in front of her. "Tell me the name. I'll go while you rest." She looked at his brown eyes. He had pulled her from the closing temple. He had gone down when she stopped moving. But the name was her mother's last secret. She could not give it away. Not yet. "No," she said. "I have to be the one." Caspian did not argue. He rose and crossed to the shelf. He pulled down fruit and a coconut, then knelt at the cold hearth. He struck a spark into dry moss. The moss caught. As the flame grew, a small lizard slid out from the woodpile, its scales a bright hot pink that glowed like the fire itself. It flicked its tail and darted along the wall. Caspian watched it a moment, then turned back to the fire. "Eat," he said. "Drink. Sleep if you can. You're no use to anyone dead." Marina ate the fruit he pressed on her. She drank the coconut water in long swallows. The warmth from the hearth reached her cold legs, where her mother's green scales caught the light. Slowly her breath came easier. Her hands stopped shaking. Outside, a blazing bird with red and orange wings landed on the sill, watched them, then lifted away. She slept. When she woke, gray light had softened to gold. Caspian sat by the door, whittling a strip of driftwood. He looked up. "Better?" Marina stood. Her legs held. She took one step, then another, across the whole floor. No shaking. No fold. The weakness was gone. "I can walk," she said. "Then walk." He set the driftwood down and stood. "But I'm coming. Not for the name. For you." She did not stop him this time. She folded the oiled cloth and pushed it into her waistband of palm leaves. She stepped out of the cabin onto solid ground. The island stretched ahead, all brush and rock and hidden paths. Somewhere in it lived the man her mother had chosen to trust. "This way," Marina said, though she did not yet know the way. She only knew she could move now, and that was enough to begin. Caspian fell in beside her. Together they left the shore behind and started inland to find him.