Eerie, terrifying, and unputdownable, <I>The Ruins</I> is Scott Smith's first novel since his acclaimed debut <I>A Simple Plan</I> earned rave reviews and stormed best seller lists.<P><I>The Ruins</I> follows two American couples enjoying a pleasant, lazy beach holiday together in Mexico. On an impulse, they go off with newfound friends in search of one of their group, the young German who, in pursuit of a girl, has headed for the remote Mayan ruins, site of a fabled archeological dig.<P>This is what happens from the moment the searchers, moving into the wild interior, begin to suspect that there is an insidious, horrific "other" among them.