A couple, Carter and Meghan, decide that they should hire a live-in sitter so that they can both work and support their two children, Max and Casey. Abby Reed answers their advertisement and they move her in immediately. After some initial rough spots with the kids, the family warms to Abby.<ref name="terrorhook" /> Abby seems obsessed with Carter, and when she helps organize a company party for a big success — that is rained out — she's in tears and distraught over the failed party. Carter's friend Tate tries to take advantage of Abby in her upset state, and then Tate is discovered dead in a car accident. Neighbor Mel is then suspicious of Abby, and is soon found dead as well, electrocuted in her bath. Then, Meghan's friend Shawna, now suspecting Abby as well, threatens disclosure as the final moments of Abby's plan to replace Meghan unfold.