While preventing an asteroid from hitting Metropolis, Superman discovers a powerful alien robot named the Prometheon, which ends up falling into Metropolis in the asteroid's place, and causing trouble because of course. General Hardcastle tries to destroy it with missiles, which has about as much success as you'd expect, while Professor Hamilton wants to try using heat-absorbing chemicals (like the kind in ice packs) to take advantage of the fact that the Prometheon is powered by thermal energy.
Superman lures it into the ocean using a red-hot iron bar so Hamilton can freeze it properly, and the crisis is averted.
- A.I. Is a Crapshoot: The Prometheon was built by aliens for heavy labor and be powered by heat. It turns on them due to it craving more.
- Attention Deficit... Ooh, Shiny!: The Prometheon wasn't built to be intelligent and can be easily distracted with a heat source.
- Fantastic Racism: General Hardcastle doesn't hide how much he distrusts Superman.
- Kill It with Ice: Superman and Hamilton plans to freeze the Prometheon so that it will stop from drawing its energy source.
- Shout-Out: The design of the Prometheon is a fairly direct lift from a page in New Gods.