Pastor Ochs was one such.

Macke read his letter again. It was addressed to the Justice Minister, Franz Gürtner.

Dear Minister,

Is the government killing handicapped children? I ask you this question bluntly because I must have a plain answer.

What a fool! If the answer was No, this was a criminal libel; if Yes, Ochs was guilty of revealing state secrets. Could he not figure that out for himself ?

After it became impossible to ignore rumours circulating in my congregation, I visited the Wannsee Children’s Nursing Home and spoke to its director, Professor Willrich. His responses were so unsatisfactory that I became convinced something terrible is going on, something that is presumably a crime and unquestionably a sin.

The man had the nerve to write of crimes! Did it not occur to him that accusing government agencies of illegal acts was itself an illegal act? Did he imagine he was living in a degenerate liberal democracy?

Macke knew what Ochs was complaining about. The programme was called Aktion T4 after its address, Tiergarten Strasse 4. The agency was officially the Charitable Foundation for Cure and Institutional Care, though it was supervised by Hitler’s personal office, the Chancellery of the Führer. Its job was to arrange the painless deaths of handicapped people who could not survive without costly care. It had done splendid work in the last couple of years, disposing of tens of thousands of useless people.

The problem was that German public opinion was not yet sophisticated enough to understand the need for such deaths, so the programme had to be kept quiet.

Macke was in on the secret. He had been promoted to Inspector and had at last been admitted to the Nazi party’s elite paramilitary Schutzstaffel, the SS. He had been briefed on Aktion T4 when he was assigned to the Ochs case. He felt proud: he was a real insider now.

Unfortunately, people had been careless, and there was a danger that the secret of Aktion T4 would get out.

It was Macke’s job to plug the leak.

Preliminary inquiries had swiftly revealed that there were three men to be silenced: Pastor Ochs, Walter von Ulrich, and Werner Franck.

Franck was the elder son of a radio manufacturer who had been an important early supporter of the Nazis. The manufacturer himself, Ludwig Franck, had initially made furious demands for information about the death of his disabled younger son, but had quickly fallen silent after a threat to close his factories. Young Werner, a fast-rising officer in the Air Ministry, had persisted in asking awkward questions, trying to involve his influential boss, General Dorn.

The Air Ministry, said to be the largest office building in Europe, was an ultra-modern edifice occupying an entire block of Wilhelm Strasse, just around the corner from Gestapo headquarters in Prinz Albrecht Strasse. Macke walked there.

In his SS uniform he was able to ignore the guards. At the reception desk he barked: ‘Take me to Lieutenant Werner Franck immediately.’