Pellegrino and Zebrowski hang a whirlwind of ideas within the framework of the traditional sf concept of first contact with intelligent aliens. Their yarn is full of action and danger to the human race, too--and without dividing the cast into good guys and bad. Among their double handful of ideas are concepts concerning enhanced human intelligence, several superweapons, new energy sources, and the "Titanic" disaster (on which Pellegrino is a recognized expert). All of this does not make the book's plot easy to follow. On the other hand, all the idea mongering shows so much creativity and knowledge that you almost wind up not caring whether the book has a plot. Pellegrino and Zebrowski are working territory not too far removed from Arthur C. Clarke's, and anywhere Clarke is popular, this book should be, too.