The Cloud — Ray Hammond

2033. The first alien radio transmissions have been received on Earth -- a torrent of encrypted information that no human or computer can crack. But the decision to reply is made, and messages of goodwill are beamed into deep space. Thirty years later, just as humankind is expecting a reply from the aliens, the signals disappear. Then scientists detect a space cloud approaching the solar system at high speed. Immense in size, immeasurable in power, this blazing storm of energy is on a collision course with Earth. As one man desperately struggles to decode the original transmissions, Earth prepares to launch a nuclear attack against a seemingly unstoppable foe. As the cloud rages through the solar system, the alien code is finally broken -- and mankind realizes that the enemy is far closer than they knew….