Disgrace 4 Episode 12

Despite admitting to Siegfried Kircheis his awareness of Christopher von Basel's role as the leader of a thyoxin trafficking organisation, Michael von Keyserling refuses to testify against him. Kircheis then visits Johanna von Basel, who reveals that she was already aware of her husband's wrongdoings and was in fact the mysterious informant who tipped the police of Kreuznach III about the imminent arrival of the leader of the thyoxin trafficking organisation.