A Dangerous Weapon

DEDEP strikes back! They have engaged the Swarm in several skirmishes and inflicted a number of casualties against the Enemy. They have also captured one of the invaders' warships and used it to good effect. And two new members to the secret society have contributed to the defense significantly.
Meanwhile, the mystery of the Dangerous Weapon is finally resolved, and DEDEP seeks to enlist it in what is hoped to be the final show-down between humankind and the aliens.
Third book in the trilogy.