A container of polonium is already in London, in the hands of a former FSB officer—now a defector, Vitovchenko. A multi-step operation by Western special services to discredit the secret organization of Russian veteran intelligence officers “Shield and Sword” has begun. To carry out such an operation, you need to have someone of your own within the organization—the “mole.” Colonel Karaev is tasked with checking every member of the organization, and all of them are proven and absolutely reliable people. Nevertheless, there is a “mole” among them, and to identify him, you must find an unconventional way. The colonel decides on a risky step…