News about attacks on cash-in-transit guards have unfortunately become commonplace in our time, but this event literally shook the public: one employee of a well-known cash-in-transit service was killed, and another was seriously injured. The bloody crime was carried out so precisely and smoothly that investigators cannot help but suspect: the robbers have an informant among the guards. They are only unaware that much more money was stolen than is indicated in the documents: there was "black cash" in the car, which the authorities should not know about. The head of the cash-in-transit service decides to secretly infiltrate his own person, Vadim, a former comrade, into the group of guards. His task is to identify the traitor who cynically works on "both fronts". The difficulty lies in the fact that motives and opportunities exist practically for everyone...