On April 19, 1861, President Lincoln proclaimed a blockade of Southern states that had seceded from the Union. The stage was set for men to use stealth to get wares to Cuba and supplies to the sons of the South. Down in Crystal River, Florida, people do all they can to stay alive, and the businessmen do all they can to make money. Two businessmen need to transport goods by ship, Captain Jim Blackworth is called. He has a new scow called The Spirit, and he knows his way around the dangerous Florida coast. He claims that, at night, no one will know where he is; the Indians call it the "art of invisibility." But first, the captain needs a fourth crew member to succeed. He finds what he's looking for in a young man named Red who's tough and self-sufficient. Soon, the captain and his crew set out on the dangerous adventures of the high sea while the Civil War rages back home. Can they avoid detection as they help Crystal River's good people survive, or will an ocean battle sink The Spirit and her dedicated crew?