Connoisseurs of film tedium know that The Poseidon Adventure ushered in the Disaster Cycle and has much to answer for, and that its numb-dimensional characters were leaden nonentities for whom death could be no adventure, despite the strivings of Shelley Winters, Red Buttons, and other typed talents. Now these very characters (even Shelley Winters' dead body) have been plucked from the smashing olio of special effects and placed back upon the Poseidon which, marvelous to say, is still afloat. And still upside down from a Mediterranean tidal wave. Readers of the original novel will recall that the ship sank therein, but that in the movie some six passengers escaped from the liner's still bobbing carcass. To accommodate producer Irwin Allen (who is filming a sequel), Gallico has written a continuation of the movie (not a sequel to his novel) and is necessarily forced to build upon the weakest part of all that has gone before: the people. Reader, they have not grown in human verisimilitude. Nor do the new characters possess that spark which divides the living from the dead. Zombies, all, in fact. Deep in this chaos rests a secret arms shipment and a half billion dollars in gold bars. Dutch and Russian salvage pirates descend onto the hulk which is guarded by Rogo, New York cop. A huge live tiger (yes!) roams the upside down world as a battle rages room by room with time out for lust as two girls show up, and then a marine volcano rises and sucks down the Poseidon in a climax too shallow for deep disgust. Remember The Deep? Call this one The Depths.