With Grim Jr. having rescued his sister Minimandy from HIM in the Realm of Flesh and Blood, and Minnie having been rejected from Heaven for the sin of loving her brother the two siblings have been returned to Halloween Town where they battle the merged form of their out of control bodies the Demon Reaper.
Minnie arrives shortly after and having failed to stop the Reaper with the Nergal Language she is also sucked inside. There with the aide of Nergal Junior pulls his sister to safety and together they order the beast to stop which buys Dan Phantom the opening he needs to annihilate the Reaper, allowing Minnie to hand control over to Junior.
Jack Skellington is able to lead a search party that finds the bodies of Minnie and Nergal, using which they construct a Ragdoll body for Minnie's soul to inhabit. Dan impressed Mandy during the battle enough that she sleeps with him and impregnate her with his Children. Junior takes his sister to the Realm of Malebolgia to pick Necropollins as a apology for the way he acted.