After the death of his wife, Simon Fuller moves to a new home, with his two daughters. One day, his daughter introduces a new imaginary friend - Nathaniel. She 'gives' Nathaniel to her father, telling him he can keep the boy "forever". Simon tries to find out who the boy really is, but is unable to. Questioning his daughter, she tells him, again, that it's Nathaniel, but he prefers to be called by his nickname, Mr. Boogie.

1887, London: Percy Townsend doesn't want to be married and doesn't want to follow in his father's footsteps and take over as head of the family business. 2014, Denver: Callie Emerson just wants to make it through her senior year of high school alive. Neither of them are prepared for being introduced in the girl's restroom at the mall when Percy inexplicably finds himself in the twenty-first century, and Callie's not too eager to help him get back home.