Andrew Miller is a paradoxical novelist. He writes eloquently about isolation in a way that feels modern and relevant, and yet, more often than not, he dips into the past in order to do so. He does it again in his eighth novel, Now We Shall Be Entirely Free. Set in 1809, the story begins with the return to Somerset of Captain John Lacroix, an English soldier who is brought home semi-conscious from the abysmal Spanish campaign against Napoleon. Lacroix is insensible for days, but even when his strength returns, his nerves remain broken and he cannot speak about what he has seen during the murderous conflict. When a fellow officer arrives in England shortly afterwards and tells him, politely but firmly, that his colleagues are outnumbered and that he needs to return to war as soon as he can, Lacroix leaves for the Hebrides, looking for solitude and to flee a life he no longer wants.

There Lacroix is taken in by a group of enlightened freethinkers and starts to fall in love with one of them, Emily. However, he does not realise that he is under threat: in Spain he has been scapegoated by the British Army for an attack on a village owned by a senior Spanish politician. A vicious corporal named Calley is sent to Britain, accompanied by a Spanish witness, to hunt him down and murder him.

Now We Shall Be Entirely Free (a title more reminiscent of a Dave Eggers novel than one by the author of Oxygen and Pure) has many of the qualities of a thriller. The story shifts between Lacroix’s journey to the Hebrides and his growing relationship with Emily, and Calley’s journey to England and then to Scotland. Calley is an entertaining character, with several qualities borrowed from the Book of Thriller Psychopaths interlaced with some neat individual touches, making him pleasingly, but not overly, familiar. Having been raised in a foundlings’ gulag in London in which the children were given dangerous work and little food, he is a runtish, emotionally deadened character who nevertheless feels loyalty to the army, his adopted parent. Despite being ‘boy-small’, he terrorises those he meets, displaying the kind of immediate viciousness that is in almost no one’s make-up: ‘there were very few he thought he could not take, if only because of his willingness to start at a pitch most had no stomach for’. Through a combination of threats and violent assaults, he inexorably makes his way towards Lacroix’s new idyll.

Miller is interested, as a novelist, in the way in which physical defects and traits affect personalities. His debut, Ingenious Pain (1997), and his 2015 novel, The Crossing, contain protagonists who respectively cannot feel pain and have an immensely high tolerance to it. In this work, Lacroix’s hearing has been damaged by the war and Emily is going blind from cataracts. The result, for each, is heightened vulnerability and a slight withdrawal from a world that can no longer be fully perceived. Miller’s prose and dialogue make no obvious efforts to belong to the time in which the novel is set, and instead Miller relies on his copious and lightly displayed knowledge of period detail to give a flavour of the era.

Now We Shall Be Entirely Free is, broadly speaking, successful. Miller’s immersion in so many different subjects – Spain, the Enlightenment, the history of shipping, the great differences in culture between various parts of Britain – is so neatly displayed that it is easy to miss how impressive it all is. The pacing is also generally good, and the story feels authentic – and yet the novel does not cohere into a great deal more. This is partly owing to the character of Lacroix, which never develops as fully as it promises to, with the result that we spend a lot of time inside a life that has an insufficiently detailed interior. It is also partly owing to the book’s structure. Miller opts for straightforward converging lines, shifting between Calley and Lacroix as they are gradually drawn together. The dramatic quality could have been retained (or even enhanced) by a bit of variety: the novel might have gone somewhere else, either back to the war or to some other plotline, to give a more organic feel to something that begins to seem prescriptively tailored. That said, it never flags and the conclusion is well done. In the end, the reader is left unchanged but with a sense of having enjoyed a brief and worthwhile exposure to a handful of obscure, troubled lives.