'American Dirt' explores the experience of attempting to illegally cross the US-Mexico border, a journey which thousands of migrants make each year. Yesterday, Lydia had a bookshop. Yesterday, Lydia was married to a journalist. Yesterday, she was with everyone she loved most in the world. Today, her eight-year-old son Luca is all she has left. For him, she will carry a machete strapped to her leg. For him, she will leap onto the roof of a high speed train. For him, she will find the strength to keep running.