To make ends meet, single mother Chloe takes a job as a live-in nanny for the cold-blooded tycoon's son, a boy with selective mutism. She is stunned to discover that the withdrawn, autistic heir looks identical to her own sunny, cheerful daughter, Mia. It turns out that her twin son did not perish in the hospital fire all those years ago. When the two lookalike children accidentally meet in a bathroom, they hatch a plan to swap identities. The bright and fearless daughter takes her brother's place in the gilded cage of the wealthy household—outwitting rivals and tormenting the wicked stepmother—while the autistic boy, bathed in Chloe's motherly love for the first time, speaks his very first word: "Mommy." A whirlwind of swapped identities, mansion intrigue, and heart-fluttering romance is about to begin.
