At half past five in the afternoon Tuấn unloads the last sack of feed in front of shed three. It weighs thirty kilos. He sets it on the pallet. He counts eleven full pallets for tomorrow's shift.

Bình is working on the electrical panel next to the filtration tank. The tank collects the slurry from the pigs in the shed. It is two metres deep. It is covered by a wide-mesh iron grate. Below the surface the recirculation pump turns slowly. The pump makes a low, steady sound, the same for seven years.

The rules are posted on the wall by the entrance. They say to cut the power to the shed before opening the panel. They say not to work alone on the tank. They say to keep the mask on the hook by the door. The mask is on the hook. The power is on. Bình is working alone because the shift ends at six and the panel still has to be closed.

Tuấn lines up the sacks on the pallet. From outside he hears the shock in the way Bình stops tapping the screwdriver.

Bình opens the panel door. The screwdriver is wet. He touches the terminal at the top left. The shock takes him in the right hand. Bình buckles at the knees. He strikes against the grate. The mesh gives way. Bình slides into the tank. The black water closes over his head.

Tuấn reaches the edge in four steps. He calls Bình by name. He waits. There is no answer. There is the pump turning. There is the smell rising from the open tank, sweet and heavy, and it grips the throat.

Duy goes down first. He sets his foot on the iron ladder fixed to the inner wall. He goes down one rung. He goes down a second. At the third his head goes back. His hands leave the iron. Duy falls into the water beside Bình. He does not come back up.

Long goes down after Duy. He gets halfway down the ladder. He stops. He opens his mouth. No voice comes out of his mouth. Long lets go and falls.

The shift leader shouts from the far end of the shed. He shouts that it is the gas from the slurry. He shouts not to go down. He shouts to wait for the firemen.

Tuấn does not go down. He takes the rope for the sacks, coiled on the hook of the beam. It is a yellow nylon rope, twelve metres long. He ties it in a wolf's-mouth knot, the knot his father taught him in the village for tying up the boats. He passes one end around the post of the lean-to. He pulls the knot tight. It holds. He puts one foot on the first rung of the ladder. The other foot stays outside, on the beaten earth.

He lowers the rope into the tank. The rope touches the black water. Tuấn moves it slowly from right to left. The rope finds an arm. A man grips it. He is one of the two who went down last, the one who stayed near the ladder. Tuấn pulls. The rope goes taut. It scrapes against the edge of the grate. The man climbs one rung, then another. He reaches the concrete. He vomits. He breathes.

Tuấn lowers the rope a second time. He moves it. He finds a hand that closes. He pulls. The second man climbs up. His eyes are red and shut. He coughs until he doubles over. He breathes.

Tuấn lowers the rope a third time. He carries it to the centre, where Bình fell. He moves it. The rope comes back empty. He carries it to the left, where Duy fell. It comes back empty. He carries it to the right, where Long fell. It comes back empty. Tuấn holds the end in his hand and does not let it go.

The firemen arrive with breathing sets at twenty past six. Before going down they measure the air inside the tank with a probe instrument. The instrument sounds. The fire chief reads the number and shakes his head. Then they throw the main switch of the electrical panel. They stop the recirculation pump. The low sound ends. They open the whole iron grate. They fasten the harness to the first man. He goes down with the mask and the double safety line.

They bring up Bình. They lay him on the concrete beside the tank. A fireman opens his jacket. He presses on his chest with both hands. He counts out loud. He presses. He counts. He presses. At the thirtieth he stops and looks at the other. The other shakes his head, no.

They bring up Duy. They lay him beside Bình.

They bring up Long. They lay him beside Duy.

Five do not come back up with breath. Two are breathing, sitting against the wall of shed three, with the orange blanket over their shoulders. One asks for water. They give him water. The ambulance loads the two who are sitting. The shift leader stays on his knees beside the five laid out. He does not cover them. He waits for them to bring something to cover them with.

Tuấn stays on his feet. He still has the end of the rope in his hand. The wolf's-mouth knot holds around the post. Tuấn unties it with his fingers. He coils the rope in twelve turns, the way it is coiled. He hangs it back on the hook of the beam of shed three. Then he looks at his hands. The left glove is torn on the finger. He pulls it off. He puts it in his pocket. The electrical panel is still open against the wall. The power is off now. Bình's screwdriver is on the ground, beside the tank.