A submarine's ruinous run in has the X-Venture Xplorers holding their breath as they submerge themselves into a marine mystery, chasing after a sinister saboteur. Spectacular trials await those trying to get an inkling about what went down! The Professor had no idea about the dangers the X-Venture Xplorers would have to face when he sent them looking for an armed aggressor, but with a little skill and a lot of luck, our plucky protagonists will surely make it through the inky depths, regardless of whatever gets to grips with them! Won't they?