David Wachter, clerk to the official war historian, arrives on the island of New Aachen early in May 1945. 

The war in Europe is ending, but the war against the Japanese continues. Wachter joins a group of war correspondents, photographers and an artist visiting the island. New Aachen had been captured by the Japanese in 1942, its Australian defenders massacred. One of the survivors was Lieutenant Connellan, now a cynical staff officer responsible for the visiting correspondents. 

They observe the war being fought by a small force, including the South Australian Militia battalion, the ‘Magareys’, and a Victorian AIF battalion, the ‘Brownlows’. In a week on the island the correspondents confront how they can – and can’t – depict the truth of war. 

Wachter, a discharged veteran of Alamein, learns that the tired troops feel demoralised by having to fight with little support against isolated Japanese on a remote island. He finds that the Brigadier commanding the Australian force is trying to revive morale by holding a footy carnival. 

Wachter sees the morale-sapping antipathy between mostly-conscripted Militia and the all-volunteer AIF troops The rivalry brings on a crisis in the front line. Despite his desire to remain an observer, Wachter becomes increasingly drawn into the developing calamity. Militia are now permitted to serve up to the Equator, and New Aachen is on the Equator. 

What will happen when disaffected Militiamen reach that imaginary line? Teams from the AIF and Militia play the final Australian Rules match, using the island's only ball – traditionally called ‘the Sherrin’. The Militia team loses narrowly. Their battalion is about to launch an attack on a steep, sugar-loaf knoll also nick-named the Sherrin: located just across the Equator. Some Militiamen refuse to attack, claiming that they are not allowed to operate beyond the Equator. 

Wachter persuades them to advance, and soon after they face a Japanese counter-attack. The Militiamen fight for their survival. In the aftermath of battle the Militiamen discover the remains of the Australians massacred in 1942. The discovery induces Connellan to move to kill a group of Japanese prisoners. The dilemma is resolved by a group of soldiers whom Wachter has met earlier in the story. Meanwhile, the cameraman Priest (based on Damien Parer), is wounded – blinded. 

The Sherrin is a novel of war and sport. It reveals the world of Australians at war in the islands, revelling in the vigorous language of a vanished Australia to explore what they knew and felt, and how their experience was recorded and expressed, in words and images.