Willie and Charley look after Spider Davis' pit pony, Zack, after he falls ill. Willie asks Helen Borso for some special healing medicine for the horse and asks Mollie and Angus to help him care for Zack. But after Doyle takes the horse back to work in the mine prematurely, Willie must confront his fears of the pit by venturing down into the mine to give Spider's horse the medicine it needs to survive.