In the prequel film, The Babysitter, Melanie was both neighbor and friend of series protagonist Cole and aided him in his struggle against the main antagonists of that film, Bee, Allison, Sonya, John and Max - each who were attempting to kill him after he witnesses and subsequently botches their Satanic ritual. However, sometime after, Melanie meets with and tells Bee that she wants in on another ritual in order to increase her online followers from a million to a billion.
A couple years later, Melanie and Cole (who is still working to overcome the traumatic events of his past) have remained friends, despite the former having found a boyfriend in a jock named Jimmy. Seeing that Cole is stressed, the villainess offers to drive him up to a boathouse for the weekend to help get his mind off things. The boy agrees, but is discouraged when he finds that Jimmy and his friends, Diego and Boom Boom, will be tagging along.
Things nonetheless go from bad to worse at the boathouse for Cole when Melanie lets it slip that she knew about the evil book that Bee used to perform the ritual that horrific night. Knowing that she can't put things off any longer, Melanie then murders Boom Boom by slitting her throat and makes Cole aware of her intentions. The boy is shocked and terrified even further when it is revealed immediately after that Allison, Sonya, John and Max have been revived and are working in cooperation with Melanie.
Melanie spends most of the remainder of the story attempting to kill both Cole and Phoebe (the film's female lead). At the climax, Bee makes her entrance and watches as Melanie and the four other killers perform the ritual and drink the mixture of Boom Boom and Cole's blood. However, because Cole's blood is no longer innocent after he had premarital sex with Phoebe (a milestone that none of the five villains believed would have been possible) a stunned Melanie dies a hellish death alongside her cohorts.