In the fourth installment of the fighting franchise, Boyka is shooting for the big leagues when an accidental death in the ring makes him question everything he stands for.

When a revolutionary new energy source begins to seep below the Earth's crust, the explosive product sets off giant blasts of fire and violent earthquakes. Now the creator of this new technology is the only one who can stop it.

A woman is killing off int'l bad guys (and witnesses). An ex FBI new man at the American Embassy in Sofia, Bulgaria, is put in charge of investigating the vigilante's actions there.

Boyka is back. This time he is fighting in the first ever inter-prison tournament with one knee.