All is Song, By Samantha Harvey

After her first novel The Wilderness, an extraordinary exploration of Alzheimer's, was showered with critical acclaim, the subject Samantha Harvey would tackle next has been much anticipated. All is Song begins with Leonard Deppling returning to London after nursing his dying father in Edinburgh. In mourning and lonely, having split from his partner, Leonard stays with his brother William, his wife and three children. He hopes to rebuild intimacy with his only living relative, but one who was absent from either the care or funeral of his father. Despite his brother's eccentricities and his own frustration and resentment, Leonard wants to recreate "the island of understanding" that defined their relationship in the past.

Charismatic, unworldly, William is a nebulous calm, seemingly unaware of the raging storm gathering around him. Leonard sees that his enigmatic, defiant brother has become a living embodiment of his applied philosophy, and although Harvey never mentions the philosopher directly, William is clearly drawn as a modern Socrates.

Scornful of institutional learning, William, like Socrates, talks informally to young people on the street, and also in his disused cafe. William too comes from a position of his own professed ignorance, using an exhausting dialectic method of inquiry to instruct his own life and to expose the flimsy value-systems held by others. Observing, Leonard is by turns envious, doubtful, infuriated and awestruck by William's analytical mind and his capacity for embracing humanity, while neglecting familial responsibilities and failing to recognise the consequences of his influence.

Whether William is sincere is the question that perturbs the reader and provides the tension in the novel. Acting as the counterpoise to William's stance are the opinions of the deceased father, a vicar, for whom moral certainties based on unquestioned faith are fundamental. In this contrast, Harvey draws on one of the major debates of Western philosophy. Leonard was charged by his dying father "to find out the truth about William" - a wish that alludes to whether William was involved in the violence on the day of the Poll Tax riots.

The facts are never fully revealed and the investigation results only in Leonard's feelings of inadequacy and guilt. Guilt is something of which William has no concept. But there is the added complexity of what their father called William's "something else", hinting at autism, mental illness and his extraordinary "heartrate of a crocodile".

Harvey's dense, unhurried prose is rich in characterisation and intellectual reasoning. The plot picks up pace when one of William's followers burns down a public library, citing William as his motivation.

In an echo of Socrates's trial, William's commitment to his paradoxical ideology is played out publicly, shadowed with potential devastation for the whole family. This beautifully written composition does that rare thing, of provoking free thought while scrutinising the far-reaching repercussions of such a rebellious activity.