In 1887, eleven-year-old Molly Fitzpatrick and her little sister Brigid arrive in New York City from Ireland in search of a home.  They have no parents, no money, and no inkling how they are going to survive.

They do, however, have a Leprechaun.

And so begins an immigration tale like no other. Molly and Brigid want only to find a home, but at every step the girls are pursued by Commissioner Scritchen, a vicious official on an anti-immigration crusade.  As they are chased through the city, the girls and their leprechaun leave a trail of wonders and miracles in their wake. An explosion of shamrocks growing right through the cobblestones near the Fulton Fish Market. An ancient sacred well uncovered in Central Park. A troll-like spirit under the Brooklyn Bridge vanquished.
And as Molly and Brigid continue to evade Scritchen’s clutches, their story spreads, gradually rousing the entire city of New York to confront its own prejudices, and to ponder what it means to be an American.