The Martians Strike Back! — Robert Reginald

As the war between Earth and Mars heats up, threatening the potential destruction of both parties, Alex Smith and his Martian friend, Big Guy, are caught right in the middle--between the humans and the aliens, between various factions of their own people, between the inherent difficulty of establishing communication between two such dissimilar intelligences. Unless Alex can find some way of bridging the gulf between the worlds, both sides will be left vulnerable to the threat posed by a third, much more dangerous alien race that's targeting both worlds. The stunning conclusion to the War of Two Worlds Trilogy!