It’s late summer. A warm sea breeze is blowing in Gloucester, Massachusetts. The town is filled with holidaymakers, locals and pleasure boaters. Many have been out on the water all day, trying to catch a fish, or just breathing in the air of the North Atlantic. Now, as a humid afternoon unwinds, they moor up and start heading to busy bars and restaurants. “Have a drink!” says one local. “I’m Bones,” he adds. “That’s my real name.”

More than 100 years ago, however, there was a near tragedy not too far away. In 1860, 100 miles (161km) off this shore, one of the world’s biggest steamer ships slowly began to fill with water. By sheer luck, the SS Connaught’s passengers were saved, but its haul – millions of dollars’ worth of gold coins – sank to the bottom of the ocean.

It’s because of this that a tall, neatly dressed Floridian has come to Gloucester to inspect his boat. Micah Eldred has pinned his hopes on finding the treasure of the Connaught. He is one of only a handful of people who knows exactly where the huge wreck lies – and he believes he’s figured out how to retrieve its bounty.