A German U-boat sinks in 1942. Its captain, Heinrich Mueller, and his brother Wilhelm, a former SS commando and former concentration camp guard, escape and now live a quiet and unknown existence on Amelia Island, Florida. And, as their boat is found and salvaged, Heinrich is deathly afraid that his brother's secret will be revealed, resulting in Wilhelm being tried as a war criminal for his acts of brutality while at Auschwitz. Heinrich vows to protect his brother because, he is his brother. 1872, Silverton Arizona, two brothers, Joshua and Jeremiah Templeton, ex Confederate cavalry with JEB Stuart, participate in a silver robbery, only to see Jeremiah killed in the attempt. Joshua flees but is pursued by the town's posse and Apache warriors all the while remembering stories of when he and Jeremiah were both youths, sharing brotherly adventures and happier times until Joshua makes his final decision, a decision to go back to his brother because, he is his brother. Following "Surfing Treasure's Wake" and "The Cardinal Pirate," "A Brother's Loyalty" follows best friends Marc and Jesus as each are on separate treasure hunting adventures for Nazi gold and stolen silver until Marc's long lost step brother brings all three together and challenges Marc's and Jesus' growing brotherhood until Marc too has to make a decision, a decision that will pit Marc's loyalty for his step brother against his "real" brother, Jesus. In the end, it's Joshua Templeton and Heinrich Mueller who show Marc what true brotherly loyalty is."