Dave Eggers was born in Boston in 1970. He is the author of A Heartbreaking Work of Staggering Genius, You Shall Know Our Velocity, The Unforbidden is Compulsory, How We Are Hungry, Short Short Stories, Teachers Have It Easy, Surviving Justice, What is the What, How the Water Feels to the Fishes, The Wild Things, Zeitoun, A Hologram for the King, The Circle and Your Fathers, Where Are They? And The Prophets, Do They Live Forever?

A Hologram for the King and The Circle are both currently in production for major film adaptations. Dave Eggers is the founder of McSweeney's independent publishing house, the 826 National network, and the nonprofit organisation ScholarMatch. He lives in Northern California with his family and Heroes of the Frontier is his seventh novel.

Júlia Sardà has illustrated everything from classic children's books to concept art for merchandise and video games, and covers for the likes of The Clockwork Sparrow, Rose Campion and the Stolen Secret and Beetle Boy by M. G. Leonard.

She is the illustrator of the acclaimed The Liszts, Sweep and The Problim Children, and she illustrated One Day in Wonderland: A Celebration of Lewis Carroll's Alice by Kathleen Krull. Her illustrations of classic stories include Oliver Twist, Alice's Adventures in Wonderland and The Wizard of Oz.