They'd already stumbled across the Swan, the Door, the Hydra, the Flame, the Arrow, the Staff and others - and The Others, of course - but now they faced a new enigma: the Shield. What new dangers - or opportunities - lie beyond the heavy steel door, opened only by a key so huge and heavy it took six survivors to lift it into the keyhole? Did the Shield offer shelter, contact with the outside world, a means of escape? Or was it another blind alley, an abandoned enigma, unknowable?
Inside they found a silver-robed scientist studying crystals, a spitcurl of white hair falling carelessly across his brow.
"Who are you?" they asked. "How did you get here?"