J. R. Ellis – författare

Exploring University Mathematics 1 provides information pertinent to pure and applied mathematics. This book discusses a variety of topics, including sets and functions, relativity, integers, waves, isometric problems, and digital computers. Organized into seven chapters, this book begins with an overview of the axiomatic way of introducing natural numbers that is completely satisfactory for mathematical purposes. This text then examines the special theory of relativity, which is a certain kind of geometry of four dimensions that connects three spatial coordinates x, y, z, and a time coordinate t. Other chapters consider the impact that the study of wave phenomena has had on the historical development of mathematics. This book discusses as well the development of the electronic digital computers. The final chapter deals with solving the isoperimetric problem. This book is intended to be suitable for students about to embark upon a degree course of which mathematics is a major part.

An unpopular victim. An impossible crime. A murderer on the loose.Revised edition: Previously published as The Body in Jingling Pot, this edition of The Body in the Dales includes editorial revisions.A body is discovered deep in a cave beneath the Yorkshire Dales. Leading the investigation into the mysterious death are experienced DCI Jim Oldroyd and his partner DS Carter, a newcomer from London.The deceased is Dave Atkins, well known throughout the village but not well liked. While there is no shortage of suspects, the details of the crime leave Oldroyd and Carter stumped. How did Atkins’s body end up in such a remote section of the cave? When someone with vital information turns up dead, it becomes clear that whoever is behind the murders will stop at nothing to conceal their tracks.Oldroyd and his team try to uncover the truth, but every answer unearths a new set of questions. And as secrets and lies are exposed within the close-knit community, the mystery becomes deeper, darker and more complex than the caves below.

An impossible murder behind a locked door. Can DCI Oldroyd find the key to the mystery?Lord Redmire’s gambling habit has placed him in serious debt. Determined to salvage his fortune by putting Redmire Hall on the map, the aristocrat performs an impossible locked-door illusion on live TV. But as the cameras roll, his spectacular trick goes fatally wrong…Special guest DCI Jim Oldroyd has a front-row seat, but in all his years with the West Riding Police he’s never witnessed anything like this. He sees Redmire disappear—and then reappear, dead, with a knife in his back.As Oldroyd and DS Stephanie Johnson soon discover, nearly everyone at the event had a reason to resent the eccentric lord. But how did the murderer get into the locked room—or out, for that matter?When the only other person who knew the secret behind the illusion is brutally silenced, the case begins to look unsolvable. Because as Oldroyd and Johnson know, it’s not just a question of who did it and why—but how?

A murdered crime writer. An idyllic Yorkshire town. Can DCI Oldroyd separate fact from fiction?A famous writer is found murdered at the Victorian baths in the Yorkshire town of Harrogate. In a crime worthy of one of his novels, Damian Penrose, who was appearing at the town’s crime writing festival, has been ruthlessly strangled. But with no trace of the murderer and no apparent means of escape, how did the killer simply vanish from the scene of the crime?There’s only one mind capable of unlocking this mystery: DCI Jim Oldroyd. But as he and his team quickly discover, while Penrose was popular with the reading public, he had made plenty of enemies. Feuds over money, accusations of plagiarism, a string of affairs…His route to the top left a trail of embittered rivals—and suspects. But which of them was willing to commit murder?When Penrose’s shocking death proves to be just the first of many, it becomes clear to Oldroyd that he is dealing with a calculating criminal hell-bent on revenge. He must find and bring them to justice. Before the truth becomes more chilling than fiction…

Life moves at a slower pace on the canals. But death always comes when you least expect it.The last thing DS Stephanie Johnson and DS Andy Carter expected during their much-needed canal holiday was a murder. When retired folk musician Annie Shipton is found stabbed through the neck at the helm of her barge, the couple can’t help investigating the seemingly impossible crime. Nobody else boarded Annie’s boat—so how was she killed from behind?With the method a perplexing mystery, DCI Oldroyd is summoned from Harrogate, and it’s not long before the detectives have a long list of potential suspects with a motive to want Annie dead. There’s the young cyclist she argued with over access to the towpath, an ambitious and arrogant local developer she clashed with repeatedly, an estranged husband…and more than a few lingering issues with her former bandmates, most of whom live along the canal.When a second murder sends shockwaves through the community, the locals start talking about a curse on the waterway. It seems the killer will go to any lengths to avoid detection. But can Oldroyd hunt them down before someone else becomes the next target?

He was supposed to be gone forever. Now he’s back.Ten years ago, DCI Oldroyd was the only person who could see the monster hiding behind Adam Blake’s charm. Oldroyd proved that Blake was a deadly serial killer, responsible for murdering many innocent people. Having vowed to take revenge on Oldroyd, on a crisp autumn morning Blake escapes from jail…Hours later, in the Yorkshire market town of Otley, a man is found strangled inside the old courthouse. Written in bold black ink across the victim’s forehead is a single chilling word: vindicta—revenge. Oldroyd’s blood runs cold when he picks up a call and hears an all-too-familiar voice: I’m coming for you.Oldroyd has spent years getting inside the minds of dangerous murderers to protect lives. But with a determined killer closing in, can he catch Blake once more and solve this difficult case, or will Oldroyd be the next to die?

In the ancient city of York, winter brings Christmas markets, cold weather…and murder.Snow dusts the cobbled streets of York as tourists flock to its famous Christmas markets. But for DCI Oldroyd, what starts as a peaceful evening on a ghost tour quickly turns deadly.The tour guide’s grim discovery is no theatrical performance—he finds the body of Henry Marlow, a notorious local landlord, in the doorway of a derelict building. Oldroyd soon has no shortage of suspects: a resentful ex-wife, angry tenants, and even the guide who knows every secret passage of the old city.As festive lights sparkle above the narrow passageways of York, darkness gathers below when a second body is found in the shadow of the ancient cathedral. Can Oldroyd untangle the web of secrets and lies before anyone else dies? As the holiday season approaches, it seems the killer is planning on making this a Christmas to remember—for all the wrong reasons…

A murder in a locked garden. A village full of secrets. Can DCI Oldroyd find a killer who has vanished into thin air?When a woman is found strangled in the locked garden of historic Bishop Hewick Hall in Yorkshire, DCI Jim Oldroyd needs to solve a seemingly impossible murder. The only door was bolted from the inside and the kitchen garden walls are too high to climb. If no one could enter or leave, how did the killer commit the crime and escape?As Oldroyd and his team investigate the victim’s past, they discover Clarissa Morden wasn’t the kind elderly woman she appeared. Instead, she was a ruthless blackmailer who kept coded records of her neighbours’ darkest secrets. Her list included a local cabinet maker, the Bishop Hewick Hall manager and even her next-door neighbour—suddenly it seems as if half the village has a motive for murder.When a second body is discovered in the local river, it seems this quiet corner of Yorkshire may never be the same again. Can Oldroyd unlock the secret of the impossible locked garden murder and find the culprit? Or will the killer strike again in this tranquil village to keep their secrets hidden…© 2026 by J. R. Ellis, all rights reserved.

A priceless violin. And a dark secret someone is prepared to kill for.Revised edition: This edition of The Quartet Murders includes editorial revisions.DCI Oldroyd has seen his fair share of victims, but he has never witnessed a murder—until now. When world-famous violinist Hans Muller is shot and killed during a concert, the detective is faced with a case beyond logic. The culprit is nowhere to be found—and the victim’s priceless violin has disappeared too.As Oldroyd investigates the mystery of the murderer’s identity and the motive for the killing, he enters the ruthless world of wealthy instrument collectors and stumbles upon a dark path where shocking secrets have been buried in the past. But the secrets will soon take centre stage.Oldroyd must use all his cunning to recover the priceless instrument. But can he also solve the mystery of a murderer who vanished in front of his own eyes?

In a Yorkshire Dales village everyone has a motive for murder—except the killer.A retired judge is shot dead outside the Dog and Gun inn in the remote Yorkshire village of Niddersgill. There’s a witness who saw everything, and the gunman’s on the run; the case should be open-and-shut for DCI Jim Oldroyd. But the murderer had no motive for wanting Sandy Fraser dead and, what’s more, no trace of him can be found.As Oldroyd and his team cast the net wider, they discover that Fraser wasn’t without enemies in Niddersgill. As the wealthy owner of a grouse moor, he’d clashed with farmers, debtors, hunt saboteurs and blackmailers. But none of them were at the scene of the murder. And when a local shopkeeper is gunned down in a second senseless attack, it’s clear that these killings are anything but random.Surrounded by the dramatic beauty of the Yorkshire Dales, Oldroyd faces a race against time to connect the crimes and find who’s behind them. But with all the evidence sending him down dead ends, can he get one step ahead before someone else is killed?

A murder with three witnesses. But one of them doesn’t believe what she saw…Halloween, Whitby. DCI Jim Oldroyd’s daughter Louise is in town with friends for a goth festival. But their visit to an escape room ends in bloody murder when one of the group stabs his girlfriend and flees the scene. It’s a crime with three witnesses—but Louise refuses to take what she saw at face value.Oldroyd and DS Carter are called in to solve the case, assisted from the sidelines by Louise. But the closer they investigate, the more complex the web of deceit appears. This is no straightforward crime of passion.With a violent murderer on the loose, it’s only a matter of time before they strike again. And this time it’s personal. Oldroyd must expose the truth, protect his daughter and stop the horror before it’s too late.

A puzzling locked-room mystery that puts someone Oldroyd loves in terrible danger…When a film shoot on Wharfedale’s vintage railway turns into a grisly crime scene, DCI Oldroyd’s idyllic visit to the countryside with his partner Deborah is well and truly stopped in its tracks. One of the film’s stars has been shot dead in a train carriage while the cameras rolled outside. But nobody else went in—or came out. Has the killer really pulled off the perfect, impossible crime?Scouring the victim’s past for clues, Oldroyd soon unearths a string of heartbroken lovers and a mountain of unpaid debts, each adding to the growing list of suspects. But before he can determine who the culprit is, there’s the small matter of figuring out how they did it. A potential connection to a previous tragedy offers Oldroyd a much-needed lead…Whoever the perpetrator is, they are ruthless and determined to avoid detection, and when a railway worker starts joining the dots, they are quickly silenced—for good. But as Oldroyd gets ever closer to the truth, it’s only a matter of time before he is given a chilling warning to back off.Perhaps Deborah should have stayed somewhere safe…