Green Lantern's old friend Rex Mason, now working for a shady industrialist, suffers an "accident" arranged by his jealous employer and is transformed into the superhero Metamorpho.

The Justice League returns from a mission in space to find the world transformed – a result of villain Vandal Savage feeding information to his younger self in the 1940s, allowing him to help take over the world during World War II. The League travels back in time themselves to stop him, and fight Nazis alongside DC Comics' WWII-era heroes (including Easy Company, the Blackhawks, and Steve Trevor).