Balthazor encounters an enigmatic man who also hopes to demolish the drill. But their joint scheme to kill the drill may inadvertently demolish something else entirely: Mandy's 15th birthday bash, not to mention a most unusual mother-daughter event.
Tina must entertain the wife of a Japanese businessman working with Balthazor's boss, but trouble looms due to a personality mix-up, ultimately jeopardizing the Hellmans' mission on Earth.
Balthazor neglects son Josh, upsetting the boy. Meanwhile, a British scientist signs on to work on the dreaded drill, and Killbride conjures up a secret initiative to collect dogs in exchange for guns.
Tina's hellish parents visit the Hellmans, but Balthazor goes overboard trying to impress the patriarch. The in-laws worry that Tina and the children will embrace humankind, so they weave a scheme to take the family back to hell.
Various obstacles keep Balthazor and Tina from celebrating their wedding anniversary. Meanwhile, there's bigwig Killbride, who schemes to have a big business initiative approved by exploiting a female EPA exec's interest in Balthazor.
Mandy starts to date Killbride's son and Balthazor uses this opportunity to get closer to Killbride.
Balthazor joins his boss on a golf outing, while the family struggles to fit in with the humans.