A prince of the mythical world starts a rebellion against humanity in order to rule the Earth. Hellboy and his team must fight to stop him from locating the all-powerful Golden Army.
As a war between humankind and monstrous sea creatures wages on, a former pilot and a trainee are paired up to drive a seemingly obsolete special weapon in a desperate effort to save the world from the apocalypse.
Three years ago, entomologist Dr. Susan Tyler genetically created an insect to kill cockroaches carrying a virulent disease. Now, the insects are out to destroy their only predator, mankind.