A sealed donation arrives at Bellwether House with one rule: do not open the boxes until after the collector dies. When Clara Vale unpacks them, one book is missing, another has been hollowed out, and a third hides a mourning ribbon tied to a call slip for a book that was never catalogued.
Then the missing volume returns, and a historian is found dead. Now Clara must follow blank catalogue cards, locked stack rooms, and a vanished woman no one officially reported missing, before Bellwether House corrects the record in its own silent way.