Cities were crushed by the falling spacecraft—but one ship didn’t crash. It remained intact, and disgorged hordes of alien soldiers determined to fight to the death.   The abandoned vessels also contained a wealth of advanced technology. Led by David Levinson, the greatest minds of our world developed deadly new hybrid weapons. Bases were built on the Moon, Mars, and beyond.  A new generation of defenders had to be trained, for the invaders would return. In the headlong rush to prepare, however, not everyone would survive…