The documentary is set in Genoa, in the dry dock made of three tanks. Once every six months a ship's hull must be cleaned. The camera shoots a cruise liner entering the dock, towed with ropes by tug-boats up to the dock's mouth. After the mooring, deepsea divers check out the hull. Then the main tank is emptied by electric suction pumps, while workers prop up the ship with beams arranged in radial pattern at the keel line. The foul bottom is cleaned, encrustation scraped off, bolts tightened and steel plates reinforced. A coat of antirust varnish is given to the submerged part of the hull and paint to the surface over the waterline. From above, the camera shoots some workers checking the anchor's chains. Cranes never stop moving. Work goes on even at night: propellers are cleaned by the light of lamps. Finally the tank is filled again. Water falls down, as over a dike's edge. The ship floats, the beams fall down. It is the tug-boats' task to take it back to sea.