Hercules (Kevin Sorbo) is happily married with two children and a baby with Deianeira (Tawny Kitaen), with the centaur Nessus (Cliff Curtis) working with him in his farm, and helping his neighbors from problems. Out of the blue, the beautiful Iole (Marlee Shelton), from a distant land, asks for help for her village that has a hole to the underworld that is killing the villagers. Hercules decides to travel with Iole to help her people and Nessus, who is a follower of Hera, poisons Deianeira with the beauty of Iole. When Nessus attacks Deianeira, Hercules kills him and he baths Deianeira's cloak with his blood and tells Deianeira to give her cloak to Hercules to keep him faithful to her. When Hercules wears her cloak, he goes haywire and dives in the hole to the underworld. When Deianeira learns what has happened to Hercules, she jumps off the cliffs and commits suicide. Now Hercules has to find a means to return with Deianeira from the world of the dead back to the world of the living.
"Hercules in the Underworld" is probably the best movie of this franchise, with a story full of action and plot points. The chemistry of Kevin Sorbo and Tawny Kitaen is amazing, and beauty of Marlee Shelton is impressive. The plot has many twists and the conclusion with a happy ending with Zeus is perfect for the plot. My vote is eight.
Title (Brazil): "Hércules no Mundo dos Mortos" ("Hercules in the World of the Dead")