In a prologue, ex-cowboy Tully Mars is working for Cleopatra Highbourne to restore a lighthouse on the island of Coyo Loco. His trip from Heartache, Wyoming to Coyo Loco takes him through several jobs and numerous Caribbean islands. Along the way he meets interesting people who become good friends.
When wealthy eccentric Thelma Barston buys the ranch Tully works on with the intention of changing it to a poodle farm, Tully responds by flinging a massage table through her window. Thelma files charges of vandalism.
Tully packs his clothes and lucky conch shell, loads up his pony, Mr. Twain, and takes off for the southern shore. He meets captain Kirk Patterson in the Alabama coastal town of Heat Wave and signs on as an apprentice on Kirk's shrimp boat heading for Yucatan, hoping to shake the bounty hungers Thelma has sent after him. At Punta Margarita, an island south of Cuba, Tully takes a job as fishing guide for Bucky Norman - a business partner of Kirk's - at his resort, Lost Boys. He works with the head guide, Ix-Nay, a descendant of the Mayans and an expert in fishing and the territory.
Tully befriends the guard at a Mayan ruin and learns of the ancient lighthouse the Mayans used to find the channel to the island. Through the guard, Hector, he meets Dr. Destin Walker, an anthropologist who is studying the ancient lighthouse.
Tully is captivated by the sight of Cleopatra Highbourne's schooner, Lucrecia, when he sees it from the ruins. Cleopatra, who is interested in lighthouses, is seeking Dr. Walker for information about the Mayan lights. When Tully turns out to know about the lighthouse, she gives him a ride on her boat in return for his use of the lighthouse to guide her through the channel from the island. By the time the ride is over, he's convinced he knows where his future lies.
But he can't join Cleopatra, because he still works for Bucky. In the meantime, he puts the word out to his friends that Cleopatra wants to restore a lighthouse and needs a Fresnel light – also known as a bull's eye light.
Bucky wants to buy a used Land Rover from Sergeant Archie Mercer, a former British army man, and he sends Tully and Ix-Nay to pick it up. Unfortunately, Archie's assistant, not knowing he's selling the vehicle, has taken off for about a week in it. Archie gives Tully and Ix-Nay the use of his beach house while they wait.
While there, he meets Dawn, who seduces him. But following a wild night, she reveals that she is Thelma Barston's niece, and she has brought two bounty hunters with her. While she has had a crush on Tully since she was 13 years old, she also has been warned that she won't inherit her aunt's fortune if she doesn't help to catch Tully.
To get free from the bounty hunters takes all the ingenuity Tully can muster, as well as help from the many friends he has made in his travels. How he does this and reconnects with Cleopatra, makes up the conclusion of the story.
This report prepared by David Gordon