The Hellmans, a family of devils, are sent by Satan to the surface of the Earth on a vital mission: Destroy a massive drill that will invade their underworld home. But first they must blend into a suburban Texas neighborhood where the neighbors give a new meaning to the term Hell.
Looking for a bonding moment with his boss Killbride, Balthazor scores himself a golf outing at his boss' elite country club. His family accompanies him and struggle to fit in with the humans whose bad behavior both thrills and bewilders the Hellmans.
When Mandy starts to date Killbride's son Wayne, Balthazor uses this opportunity to get closer to Killbride and the drill.
Tina and Balthazor try to celebrate their wedding anniversary but are finding it difficult to find time to do so. Meanwhile, Killbride is trying to get a new business plan passed by the EPA and when he learns that the female EPA executive is enamored with Balthazor, Killbride uses him to his advantage.
Tina's parents from Hell make a visit to Earth, Balthazor makes an extra effort to impress Tina's father. Concerned that their daughter and grandkids will assimilate too well into human culture, the in-laws arrive with a plan to bring the family back to Hell.
When Petromundo attempts to show the public they care and Josh tries to stop dogs from being turned into diamonds, Balthazar has to choose between saving his son and saving hell.
Balthazor is forced to test out a new weight-loss device, a robot that insults its owner into diet submission. But that's just the beginning of the mechanical being’s reign of terror.
Tina is responsible for showing the town to the wife of a Japanese businessman doing business with Balthazor's boss, but a case of switched personalities threatens to put the end to the Hellman's mission.
Killbride decides to unfreeze the head of Atilla the Hun to handle some personnel cuts. Unfortunately, the legendary conqueror has some past business to settle with Uncle Vlaartark.
Series finale. Balthazor is recruited by a mysterious man who shares his desire to destroy the drill. But their plan will likely ruin Mandy's 15th birthday Blaargmitvah, including the eagerly anticipated mother-daughter hexagon cage match.