When the Royal twins Remus and Rinda are forced to flee by the invading Mongaul army, they are saved by a mysterious leopard-headed warrior. His name is Guin, but he has no memory prior to meeting the twins. As night falls, the group are attacked by ghouls and must once again fight for their lives.

The battle between the Sems and the Mongaul army has finally begun. Although at first the Mongaul's numerical superiority seems an insurmountable obstacle, Guin's decisive strategies allow the Sems to even the odds.

Disguised as a Mongaul soldier, Istavan manages to infiltrate the ranks of Lord Marus' men, in preparation for the next stage of Guin's offensive. While the Sems prepare for the coming battle, Guin goes in search of the Largon to recruit them to his cause. The Sems can only hold out against the Mongaul army for four days; Guin must return before time runs out.