When we last saw Thomas Cromwell, in the Booker prize-winning Wolf Hall, Hilary Mantel's unlikely hero was at the height of his powers. Secretary to the king, his job was to edit Henry's plots: to erase his queen, cancel his inconvenient daughters and terminate those chapters in the narrative which were getting tedious. Having secured the end of the king's 20-year marriage to Catherine of Aragon, enabled his remarriage to Anne Boleyn, and seen his enemy Sir Thomas More ascend the scaffold, Cromwell plans five days for himself at Wolf Hall, the home of the Seymour family. The first mention of the book's title comes as its last words, but we have been in a hall of wolves throughout.

It is at Wolf Hall in 1536 that the king, in Mantel's sequel Bring Up the Bodies, will encounter Jane Seymour, who to her family "has as much use as a blancmange" but to Henry represents a source of future sons. "What," he now wonders, "if there is some flaw in my marriage to Anne, some impediment, something displeasing to Almighty God?" Cromwell, who has heard these words before, is ordered to conclude the story of Boleyn, and to do it swiftly.

Her "flaw" is infidelity and the guilty men – "though perhaps not guilty as charged" – are Mark Smeaton, a "suspiciously well-dressed musician", "Gentle" Mr Norris, Henry's chief bottom-wiper, the aristocrats William Brereton and Francis Weston, and the Queen's own brother, George, whose tongue, his wife claimed, had been swirling in Anne Boleyn's mouth. The book closes as the king, "like the minotaur, breaths unseen in a labyrinth of rooms" while down river the sword that comes down on the queen's neck is "a sharp sigh or a sound like a whistle through a keyhole", and her "flat little presence becomes a puddle of gore".

It is not a plot spoiler to reveal that Anne Boleyn is beheaded. While it is in the nature of historical novels that we know what happens next, the genius of Bring Up the Bodies is that Thomas Cromwell – despite controlling the fates of so many – doesn't know, and the events are narrated through his consciousness.

Mantel's risk, as it was in Wolf Hall, is to tell the story in the present tense, to give us Cromwell, who will himself be dead in four years' time, not seen from above, hurtling towards his inevitable end, but living his life moment by terrifying moment in a world where every day might be the last. "1 May 1536. This, surely, is the last day of knighthood. What happens after this… will be no more than a dead parade with banners, a contest of corpses. The king will leave the field. The day will end, broken off, snapped like a shinbone, spat out like smashed teeth."

Rarely has the intelligence of a novel been so dependent upon grammatical tense. All Cromwell knows about his own history is the past, and he will often return to scenes from his youth in Putney where, the son of a violent blacksmith, he ran away to wander in Europe, returning 27 years later as a man "at home in courtroom or waterfront, bishop's palace or inn yard", able to "draft a contract, train a falcon, draw a map, stop a street fight, furnish a house and fix a jury" – most of which we see him doing. Mantel suggests that it is Cromwell's origins, together with his almost total absence of friends and family (his beloved wife and daughters have died of the plague) that allows him to play the role he does: unlike the Howards, the Boleyns or the Seymours, he has no clan to serve or name to protect but his own.

While Mantel gives us the events as Cromwell sees them, the reader is asked to see Cromwell as Mantel sees him: not the cold-eyed bureaucrat of Holbein's portrait or the ruthless Terminator of the Tudor age but as worldly, unsentimental, melancholic, and brilliantly in tune with his time, just as he would be brilliantly in tune with our own. Analogies have been made with Stalin's chief of secret police and the Inner party member O'Brien in Orwell's 1984, but Cromwell's stocky person moves through these pages more like that of a mobster. Mantel's Cromwell is a sex symbol: the kind of man women want to have and men want to be.

In a court of preening noblemen presided over by a sobbing king who cannot sire a heir, Cromwell is admired by us and hated by everyone else because, as he puts it, "I was always first up in the morning. I was always the last man standing. I was always in the money. I always got the girl. Show me a heap, and I'm on top of it."

Is Bring Up the Bodies better than, worse than or equal to Wolf Hall? While lacking, necessarily, the shocking freshness of the first book, it is narrower, tighter, at times a more brilliant and terrifying novel. Of her historical interpretations, Mantel says in her afterword that she is "making the reader a proposal, an offer", but what is striking is how little concerned she is with the reader. Her prose makes no concessions to the disorientated: a moment's distraction and you have to start the page again. Mantel, like Cromwell, seems not to mind if we are there or not: she is writing, as he was living, for herself alone.