The costs of decommissioning an oilrig after its lifespan has ended are huge. Yoho Oil believes that it has found a solution that allows defunct rigs to be decommissioned safely by developing an enzyme that feeds off prevalent harmful commodities. A cleaning crew is assigned the task of spraying the Johnny Alpha rig with the enzyme. They have 24 hours to clean it and lay explosives that will release it from the seabed. The rig's interior is sprayed with the enzyme, but, in its depths the bacteria are reacting with the remains of the oilrig’s dead cat and a breeding ground is forming fast. With the rig soon doused with bacteria, crew leader Hansen radios to the helicopter to pick them up. The reply comes back that a storm is approaching and there will be an overnight delay. Accustomed as they are to such setbacks, the crew makes the most of their situation and hold a party~ But something is moving in the lower bowels of the rig. Kim and Jacob go to the roof of the rig and are getting more intimately acquainted when they notice a stream of slime dripping from above them and hear screams from below. Carefully they make their way to the noise and are shocked by what they see! In the depths of the rig, there are giant parasites and they are growing rapidly, moving onto puddles of bacteria continually growing in size. Gio catches up with Kim and Jacob and they try to catch a vicious parasite but it spits acid in Gio's face. Kim goes for help as she recognizes this as the beginning of a mutation over which they have no control. The power suddenly runs down and the rig is cast into darkness. By torchlight the remaining group start to construct makeshift weapons out of the backpack tanks. Each carrying 'flame thrower' packs, they go to the generator room but discover that the cables that support the power have melted through in many different places and are covered in slime. Jacob slowly extends his hand towards the comer and touches something slimy and horrible. As he pulls back his hand his flesh bubbles painfully and he is hit in the face by a thick spray of acid. The parasites are certainly in control! There is just one way to be sure that all of the bugs are killed; the rig must be blown up. But where can the remaining team hide?