Lord Wrexford and Charlotte's growing family ensures that life is a source of constant adventure. The addition of Wrexford's half-sister to their household is proving an unexpected delight. But some surprises are less welcome—and trouble strikes when Hawk, one of the young boys in their care, arrives home distraught after learning that his new drawing teacher has been found murdered on Threadneedle Street.

Fletcher Campbell's death could be dismissed as a random robbery turned violent. But as an artist herself, Charlotte suspects there's more to the case than meets the eye. Closer examination reveals that a distinctive ring was taken from the victim's finger. With Hawk pleading for the family to help solve the crime, Charlotte and Wrexford suddenly find themselves entangled in a fiendish mystery that harkens back to a decade-old scandal that nearly brought down the government.

It seems Campbell's brother was the infamous leader of a counterfeiting gang that swindled the Bank of England. Most were apprehended, but forged banknotes remain a problem. Now, the Bank of England has offered £20,000 to anyone who can use the newly-invented engineering technologies to create the Inimitable Banknote—a complex design that cannot be counterfeited.

It's a prize that could tempt anyone, and Wrexford and Sloane's investigation turns even more fraught when one of their closest friends falls under suspicion. The deeper they probe, the more treachery comes to light. For when a lie so easily masquerades as truth, danger may be much closer than they think . . .