When the government forms an expedition to map the Far West, Eff has the opportunity to travel farther than anyone in the world. With Lan, William, Professor Torgeson, Wash, and Professor Ochiba, Eff finds that nothing on the wild frontier is as they expected. When spring comes the explorers realise how tenuous life near the Great Barrier Spell may be if they don't find a way to stop a magical flood in a hurry. Eff's unique way of viewing magic has saved the settlers time and again, but this time all of Columbia is at stake if she should fail.