High above the city, on an old rubble hill from World War II, stands a roughly constructed wooden cross. Slowly, the sun rises above the towers of Cologne Cathedral. But the man on the cross no longer sees the sun. He is dead. Private detective Marius Sandmann is shocked by the death of his boss, Gunther Brock. Apparently, the murder is connected to their new case, which they had taken on shortly before: the two detectives were to find a missing painting from the 15th century. A crucifixion, supposedly painted on a piece of the cross of Jesus Christ...