The Orpheus crew have found rare bio fuels in the ocean depths, but the Russian captain of the Volos submarine determined to stop them, before they bring it to the surface.
The Orpheus is fixed and Volos reactor is ok. Instead of returning to the surface they decide to find more of the rare bio-fuel samples. But The Russian captain has his own plan and instructs his men to kill the crew. In their struggle to escape, some are left behind...moreless