It began as a problem in one of Holmes' beloved beehives, led to a murderous cult, and ended - or so they'd hoped - with a daring escape from a sacrificial altar. Instead, Mary Russell and her husband, Sherlock Holmes, have stirred the wrath of those they've thwarted. Now they are separated and on the run, and pursued across the Continent by a ruthless enemy with powerful connections. Unstoppable together, Russell and Holmes will have to survive this time apart, and with Holmes' young granddaughter in her safekeeping, Russell will have to call on instincts she didn't know she had. From secret rooms in London to rickety planes over Scotland, Russell and Holmes work their way back to each other in the most complex, shocking, and deeply personal case of their career.