The "Invitation to the Chase" arrives in the post without warning. Inscribed in silver ink on black paper, the anonymous summons expresses a simple challenge: to find the priceless Templar Diamond. Stolen in 1896 from St. Peter's Cathedral in Belfast, the Templar Diamond has been missing for six years, with the suspects still at large. Now there is hope of its discovery in Boston, if the cryptic invitation can be believed. But is it a ploy? Jack Tuohay, Belfast Inspector 2nd class, is an inheritor of one such invitation. Professionally discredited for allowing the diamond theft to occur on his watch, he is desperate for a chance at redemption. But the new circumstances are not without stakes, as demonstrated by the murder of a second recipient of the invitation, a Boston priest. It seems the search for the missing diamond is a deadly one. Tuohay, with ties to both the diamond and the dead priest, is grudgingly assigned the case by his superiors. Along with two former sleuthing companions, Eliza Wilding and John Eldredge, he pursues the priest's killer and the lost diamond. It is not long before the companions find themselves entwined in a web of ciphers, puzzles and ruses where one step closer to the diamond is also one step closer to the fatal consequences surrounding it. The chase is on.