Elena Santos works as a live-in nanny for an affluent family in New York City; she quickly learns that everyone in the building has deadly secrets and ulterior motives; what they don't know is that Elena has some shocking secrets of her own.

While bonding with the other nannies, Elena learns that the Wards' previous nanny vanished without warning; Elena continues her search of The Greybourne and discovers a shocking truth.

Elena snoops around Torys apartment while helping Darcy and Bennet, which leads to an unexpected discovery in the secret room. Elena is rattled by a surprise call from her past.

Elena becomes paranoid that she's constantly being watched; Ginny and Elena bond while cleaning out Allie's closet; Elena confronts her past.

On Allie's birthday, Tory, Matthew and Jasper try to find the best way to confront their grief and honor her memory; Elena discovers someone she trusts is lying to her.

Elena sneaks into a masquerade ball hosted by the Greybounes; Roman searches Mrs. Ivey's apartment; Ginny confronts Elena about her identity.