Eleven-year-old stuttering Darby believes she's supposed to be perfect, just like her mother demands. But summer away at camp promises temporary escape. There, she befriends twelve-year-old Justin, who hasn't uttered a word since his dad died, and ten-year-old Naz, who is struggling to learn English.

When mysterious calliope music from a nearby warehouse grants the trio power to communicate without words, they sneak inside to find out why. After the abandoned building bursts into a full-sized carnival with magical rides, they're greeted by the ghost of Leroy Usher, Carnival King, who can't rest until his property brings joy to children once again. He asks for their help convincing his estranged sons and daughter to restore the carnival to its former glory before summer's end. In return, Mr. Usher promises he'll teach Darby, Justin, and Naz how to find their voices.

With each challenge they face, the kids' confidence grows, and they learn they're capable of accomplishing so much more than they ever imagined. But will it be enough to persuade the Usher siblings to bring the carnival back to life instead of selling the property for demolition?