Ring of Fire is the thirty-seventh and final episode of Godzilla: The Series that made it to air, and is the sixteenth episode of season 2.
The episode opens with the Fire Monster rising through a pipe on an oil rig in the Gulf of Mexico and attacking the workers. H.E.A.T. then goes to investigate the claims of a "combustible entity", and send N.I.G.E.L. onto the destroyed rig where he finds the Fire Monster. He is destroyed and they search it on foot. They bring projectile gas canisters that are capable of freezing lava, and use them to enter a battle with the monster in which it runs from one member into another. Just when they lose the upper hand, Godzilla arrives to combat it in their stead. They then discover that Godzilla's Atomic Ray only strengthens the Fire Monster. H.E.A.T. is able to escape just as the Rig crumbles under Godzilla's weight. After falling in the water, the Fire Monster regains energy by absorbing oil in the water and, seeing this, H.E.A.T. leads a trail of their own oil to an otherwise oil-less location to lure it away and let it deplete its reserves. They are successful, but Mendel Craven wished to study the creature more, and secretly has N.I.G.E.L. take it back to H.E.A.T. Headquarters. Randy Hernandez then joins him, and they conduct research on it in an outbuilding with the furnace where they discover that the creature bleeds methane gas, which reacts with the furnace's pilot light and explodes. They escape unscathed, but the Fire Monster returns. It attacks a nearby oil tank, and they call Anthony Hicks to help. It is then revealed that his entire arsenal is heat-sensitive, so everything the Military throws at the Fire Monster will prematurely detonate. Craven and Randy then rig N.I.G.E.L. with Nitroglycerin and send him toward the creature. They defeat it and place it in a secure environment.