The Song Before it is Sung, By Justin Cartwright

Here are two stories: one is that of Isaiah Berlin and Adam von Trott zu Solz, the leader of the plot against Hitler (masked here as Elya Mendel and Axel von Gottberg), and the other that of Conrad Senior, a journalist who has found a heap of papers written by Mendel and wants to do something creative and career-enhancing with them. The two tales only intermittently gel. While the former awes with its insight into human fragility, the latter ever so slightly irritates.

Axel von Gottberg comes across in many ways as Mendel's indulgent older brother. But the roles are reversed as Gottberg, in a bid to undermine the Nazi party from within, finds himself having to lie to the world. The aristocrat is full of dreams and painfully well-intentioned; Mendel is the cautious pragmatist, suspicious of mysticism.

Justin Cartwright's powerful and complex study of friendship built on incompatible interests will provoke and move anyone exercised by the question of how human nature survives when totalitarianism raises its fist.

Bloomsbury £7.99