Five awesome aliens have been unleashed from the darkest corner of the galaxy - and they're out to destroy the universe. Only Cosmo, a young boy from planet Earth, has the power to stop them. Recruited by the elite defence organisation G-Watch to defend the galaxy, Cosmo must prove himself and commence battle against the deadliest aliens in space. In his fourth mission, Cosmo must travel to the Paradise Planet of Oceania - where the galaxy's holidaymakers are unaware that a very unwelcome guest is on its way. The awesome underwater alien Hydronix is wreaking havoc on this peaceful holiday planet, and Cosmo must head to the depths of the ocean to do battle with this mighty monster of the deep.