When the British Museum gets Sidney and Nigel to help search at Tudor sites for a ring of king Henry VIII starting from clues in a painting, Nigel is confronted with his self-confident pestering elder brother Preston Bailey, who works there, but their resurfacing sibling rivalry -now also for a girl from their young years- is not the only danger, as at least one other suspiciously well-informed party joins the treasure hunt and soon proves violent.