Damon Galgut's Booker-shortlisted fifth novel is narrated by Frank Eloff, a middle-aged South African medic whose isolated hospital has virtually no patients. Frank and his small band of colleagues conscientiously report for duty each day, yet weeks go by without them doing anything more important than filling in forms or playing darts. This bizarre existence is disturbed by the arrival of Laurence Waters, a young doctor fresh out of medical school. Overcoming his dismay at the apparent futility of the post, Laurence determines to shake the staff out of their complacency.

The hospital is situated in the derelict and deserted former capital of one of the "homelands" - economically unproductive areas where black South Africans were handed quasi-autonomy in the time of white rule. With the collapse of apartheid, the hospital has become a disintegrating bunker for those unable to adapt to the new society being forged around them.

This setting allows Galgut to examine some of the tensions within the Rainbow Nation. At one level, Laurence represents the new idealism. His programme of outreach clinics - taking the doctors out of their empty buildings to help the poverty-stricken inhabitants of far-flung villages - initially meets with resistance. After the first, successful clinic, enthusiasm grows among most of the existing staff, though less for altruistic reasons than because of the potential for personal validation or political gain.

Frank was complicit in, and traumatised by, nefarious aspects of the old regime. His father and stepmother are paid-up members of the white elite, and their routine abuse of their black servants exemplifies the persistence of supremacist attitudes. Frank himself has an uneasy relationship with Maria - a married black woman who sells African carvings to tourists - whom he pays for sex under cover of darkness. While Laurence looks somewhat breathlessly to the future, Frank becomes obsessed by the apparent reappearance of figures from his apartheid past who, at least to his increasingly fragile mind, seem to be playing out the same, shadowy guerrilla wars, albeit to a subtly different score.

Galgut's characters are careful and subtle creations, and we are never allowed to decide who exactly is the good doctor of the title. Laurence is a restless figure who proves rigidly judgemental when it appears that the hospital's black male nurse, Tehogo, has been pilfering equipment. Despite his liberalism, Laurence's failure to accommodate other value systems more ancient and dangerous than his own is ultimately his downfall. Frank, cynical and tainted, is a victim of the apartheid that shaped him, and his life is a long retreat. In his ambivalent attitude towards Tehogo and his selfish agitation when Maria disappears, Frank strains towards an impossible redemption.

Written in measured, seductive prose, The Good Doctor is a highly allegorical work. For the most part, Galgut balances prescription and suggestion well. Frank and Laurence are both emotionally deadened men, which conveniently allows Galgut to manipulate them to his own ends. Unpalatable as Frank can be, he does engage the reader's sympathy. Laurence is more tricky, and eventually becomes little more than a cipher.

The Good Doctor transcends its setting and becomes an exploration of clashes between perspectives and the wreckage of upheaval. One might wish for a more invisible marriage of character with novelistic theme, but that should not detract from this complex and absorbing novel.

Phil Whitaker's most recent novel, The Face, is out in paperback from Atlantic Books