Rivers of London recap

Probationary constable Peter Grant takes a witness statement from a ghost at a Covent Garden murder scene and is recruited by DCI Thomas Nightingale, the last officially sanctioned wizard in England, as his first apprentice in decades. Living at the Folly, the old home of English magic, Peter learns spellcraft while investigating a wave of impossible violence: ordinary Londoners briefly possessed, driven to kill, and left with their faces destroyed. The killings prove to be re-enacting the plot of Punch and Judy, staged by the vengeful ghost of Henry Pyke, a failed eighteenth-century actor, and powered by something older - Mr Punch, the spirit of riot. Alongside the case, Peter brokers peace between Mother Thames and Father Thames, the rival deities of the river, and meets Beverley Brook. The investigation turns catastrophic: Nightingale is shot, a possessed audience riots at the Royal Opera House, and the spirit is revealed to have been riding Peter's friend Lesley May all along. Peter lays Pyke to rest, but Lesley's face is ruined. The river peace is sealed by an exchange of hostages, Beverley among them, and Peter commits fully to the wizard's life.

On a January night, probationary constable Peter Grant guards the cordon at a Covent Garden murder scene where a man has been beheaded, and takes a witness statement from Nicholas Wallpenny - who proves to have been dead for well over a century. His attempt to follow up on a ghost draws the attention of Detective Chief Inspector Thomas Nightingale, the last officially sanctioned wizard in England, who claims Peter for his tiny unit just as Peter is about to be shunted into a case-paperwork job. Peter's friend and fellow probationer Lesley May, widely rated the better officer, joins the murder inquiry on the conventional side. The killing is stranger than it looked: the attacker was an unremarkable man who struck without motive, and afterwards his face collapsed as though worn out from the inside. Sworn in as Nightingale's apprentice - the first new one in decades - Peter moves into the Folly, the grand, nearly empty Russell Square headquarters of English magic, kept by Molly, its silent and unsettling housekeeper, and begins learning that magic is real, learnable, and governed by rules, while the cryptopathologist Dr Abdul Haqq Walid supplies the forensic side of the uncanny.

Nightingale hands Peter a diplomatic problem to run alongside the murder inquiry: the two ruling powers of the river - Mother Thames, the goddess of the tidal river below Teddington, and Father Thames, the old god of its upper reaches - are pressing claims against each other, and the Folly wants the peace kept before the dispute turns into open conflict between their courts. Peter visits Mother Thames's court and meets her daughters, the spirits of London's lesser rivers, among them Beverley Brook, with whom he strikes an immediate spark, then travels up-country to Father Thames's travelling fair to hear the other side. Both courts size Peter up as a useful new piece on the board. Meanwhile the impossible assaults continue across London, each perpetrator briefly possessed, seized by sudden savage violence, and left damaged, and the pattern stubbornly refuses to fit ordinary police work. Peter's training grinds forward - Latin, the first forms, hours of practice for a single reliable werelight - and he sets up a workshop in the Folly's coach house where his modern technology can survive, since working magic and microchips do not mix.

At a puppet festival Peter finally sees the shape of the case: the string of possessions and killings is re-enacting the plot of a Punch and Judy show, with living Londoners forced into the roles and discarded. The guiding intelligence identifies itself as Henry Pyke, a resentful eighteenth-century actor murdered near Covent Garden, whose ghost is staging the drama - but Pyke is a mask as much as a man, animated and amplified by something far older and crueller that answers to the spirit of Mr Punch, riot and rebellion given a face. The Folly works the problem from both ends, researching Pyke's history to find a purchase on the revenant while the conventional murder inquiry flounders against evidence that cannot be true, and an attempt to bait and trap the ghost - with Peter himself as part of the lure - shows how dangerous the thing has become. Each new possession burns out its host, the intervals between attacks are shrinking, and the revenant has begun to take a personal, mocking interest in Peter.

The hunt goes badly wrong. An operation against the revenant ends with Nightingale shot in the chest by a possessed gunman and left fighting for his life in hospital, and with the Folly's authority suddenly in doubt. Into that vacuum steps Lady Tyburn, the most establishment-minded of Mother Thames's daughters, who regards the Folly as a dangerous anachronism and moves to have its business folded into ordinary official channels, with Peter sidelined. The possession epidemic then peaks in spectacular fashion: at the Royal Opera House, Punch's influence takes an entire audience at once, and the evening collapses into a riot that spills into Covent Garden, putting the supernatural crisis beyond any hope of discreet handling. Peter, effectively on his own - his master in intensive care, his legitimacy contested, and the city's uncanny powers watching to see what he is worth - has to keep working a case that has already consumed everyone who got close to it, knowing the revenant is building to a finale on the ground where Henry Pyke's grievance began.

The truth lands close to home: the spirit has been riding Lesley May since the night of the first murder - she was Punch's anchor all along, hidden in plain sight at the centre of the investigation. Following the possessed Lesley to the heart of Pyke's old ground, Peter confronts the revenant within the remembered London of its origin and brings Henry Pyke's long grievance to an end, laying the ghost to rest; Mr Punch himself, the older spirit that gave Pyke his power, is driven out rather than destroyed. The cost is terrible. The magic that reshaped Lesley's face for the revenant's performances leaves it in ruins when the spirit departs; surgeons save her life, but not her face or her fast-track career. Nightingale survives his wound and begins a slow recovery. The feud between the courts of the Thames is settled with a medieval solution - an exchange of hostages, Beverley Brook going upstream to Father Thames's court while sons of the old man come down to the city - and Lady Tyburn's attempted takeover of the Folly is turned back, at the price of her lasting enmity. Peter ends where he began, at the Folly, but changed: a sworn apprentice with a long road ahead, and a friend whose ruin he could not prevent.

The case closes with Henry Pyke's ghost laid to rest, though the older spirit that amplified him - Mr Punch, the spirit of riot and rebellion - is driven off rather than destroyed. The cost lands hardest on Lesley May: the revenant had been riding her since the night of the first murder, and the magic that reworked her face to its purposes leaves that face in ruins. She survives, under long-term medical care, her fast-track career gone. Nightingale is recovering from the gunshot wound that nearly killed him and resumes his duties slowly, with Peter carrying more responsibility than any first-year apprentice should. The feud between the two courts of the Thames is settled the medieval way, with an exchange of hostages: Beverley Brook goes upstream to live under Father Thames's authority, and sons of the old man's court come down to the city in return, so Peter's easy connection with Beverley is suspended just as it was becoming something more. Lady Tyburn's attempt to fold the Folly into the ordinary machinery of the state has been beaten back, but her hostility to Peter is now personal and durable. Peter himself ends the book committed: no longer a constable making a strange detour, but a sworn apprentice wizard with years of Latin, forms, and police work ahead of him.