On the distant planet Valdenia, where more than ten years ago a regiment of Yankee northerners under the command of Andrew Keep was mysteriously transported, the war between people and the bloodthirsty Bantags continues. In recent years, the Bantag have made incredible leaps in technological development, depriving the Army of the Republic of its former dominance. The Bantags become subject to the vast expanses of the sea, which allows their cunning leader Gaark to realize his insidious plan. Having undertaken a series of diversionary maneuvers, Gaark unexpectedly attacks the enemy from the sea. His plans include separating parts of the Republican army and, cutting off their connection with the outside world, dealing with each one separately.