The story of Zygmunt, a miner and member of Solidarity, who is thus involved in the opposition against the communist regime. Accused of cooperating with the secret police as an infiltrated agent (a mole), Zygmunt has to face, after the collapse of the communist system, a lustration process before the special verification committee. He denies any cooperation. But the committee will interrogate a former secret police agent, the one who personally recruited Zygmunt.