The composition calls itself the Book of the Hidden Chamber, and it is organised as a journey with a schedule. At sunset the ram-headed night form of Ra boards the solar barque and enters the western horizon; each of the twelve hours that follow is a region with its own name, gatekeepers, inhabitants and business, rendered in three registers of figures with the barque travelling the middle one, and the text names them all, for knowing the names is the book's repeated point. The early hours pass through abundance and the fields of the Nile-like waters of the netherworld; the fourth and fifth hours cross the desert realm of Sokar, where the waters fail and the barque must be towed as a snake over sand, past the hidden cavern and the lake of fire. The sixth hour is the turning point of cosmos and book alike: in the depth of night the ba of Ra unites with the corpse of Osiris, sun and dead god become one, and from that union the renewal of all life proceeds.
The seventh hour brings the crisis, Apophis the great serpent sprawled on the sandbank to drink the waterway dry, subdued by Isis's magic and Seth's spear and bound by his captors. The remaining hours gather strength, the drowned are rescued in the tenth, and in the twelfth the god is drawn through the body of a great serpent, entering old and emerging young, reborn as the scarab Khepri into the arms of Shu at dawn.