Brandt himself was obsessed with suspicions of a rather different conspiracy against him - between Herbert Wehner and the East German leadership. He recorded them in a series of cryptic notes, written at some point after his retirement but not published until 1994, and held to them for the rest of his life. They centred on Wehner's known contacts in East Berlin. Wehner reported to Brandt two meetings there. The first was with Erich Honecker, the East German party leader, and its purpose, according to Wehner, was to relaunch the secret trade in political prisoners and family reunions, which had ironically been brought to an end by the regularisation of relations between the two states in the newly signed Basic Treaty. The second was with Wolfgang Vogel, the middleman in this trade, though the subject in this case was said by Wehner to be economic collaboration in general. The timing of both meetings was unsettiing — the first on the evening of 29 May 1973, the day that Nollau told Genscher, and Genscher told Brandt, about the suspicions against Guillaume, and the second on 3 May 1974, the day that Nollau told Wehner about the list of Brandt's women. In any case Brandt believed that Wehner had had additional contacts with East Berlin which had gone unreported. In the course of them, he suspected, Wehner had been told that Guillaume was a spy, and had also been primed to launch his extraordinary attack on him from Moscow in the autumn of 1973.

Brandt's information was provided by Egon Bahr, who had obtained it from the Russians. It had come by way of the secret system of communication that Bahr had established with the Soviet leader Leonid Brezhnev, in imitation of the 'back-channels' used by Henry Kissinger to negotiate with the Soviet Union. The historian August H. Leugers-Scherzberg has recently cast more light on this dark corridor, and the allegations against Wehner that it was used to convey. What neither Bahr nor Brandt realised, says Dr Scherzberg, is that the chain of communication led through Yuri Andropov, later Brezhnev's successor, but at that time head of the KGB. Andropov had reasons to want Wehner discredited in Brandt's eyes, because Wehner distrusted the 'back-channel', and wanted to replace it with a more direct link, while Andropov himself naturally wished to preserve it as an instrument for his own influence. Wehner also dissented from Brandt's belief that an understanding with the Soviet Union was the key that would unlock relations with East Germany, and wanted to distribute the Federal Republic's efforts at reconciliation more broadly around Eastern Europe.

Whatever Wehner did or didn't do behind the scenes, however, his assurance of support for Brandt at the crucial moment in Münsteifel seems to have been less than wholehearted, and Brandt always held him responsible (together with Rut) for failing to dissuade him from a decision that he never ceased to regret.