From audible.com:

Marriage. It's a double-edged sword, or at least it is for Nikki Heat. Her husband, Pulitzer Prize-winning journalist Jameson Rook, infuriates her in a way no one else in her entire life has ever done. He also takes her to heights of pleasure she has never experienced. But most of all, she loves the man with all her heart, and she'd do anything to protect him. Which is just what she had done not so long ago. It had almost cost them everything.

Now, Rook is given the honor to be a visiting professor at his alma mater, and he can't pass up the opportunity to mentor burgeoning writers at his former award-winning college newspaper. Shortly after his arrival on campus, a female reporter for the paper is found dead - naked - in Rook's bed.

Dealing with betrayal from any man is not Nikki's style. She and Jameson have had plenty of conflicts during their complicated relationship, but none like this. Is her husband keeping secrets of his own, or can she really trust him?

In order to find out, Nikki gives Jameson the benefit of the doubt and digs into Jameson's theory of a secret society within a secret society. What she finds puts her investigative skills, and her marriage, to the test.

From audible.com:

Nikki Heat and Jameson Rook race to stop a deadly threat from Heat's past as well as an all-too-present serial killer, in Richard Castle's follow-up to the New York Times best-seller Frozen Heat.

Determined to find justice for her mother, top NYPD Homicide Detective Nikki Heat continues to pursue the elusive former CIA station chief who ordered her execution more than a decade ago. For the hunt, Nikki teams once again with her romantic partner, Pulitzer Prize-winning investigative journalist Jameson Rook, and their quest for the old spy and the motive behind the past murder unearths an alarming terror plot, which is anything but ancient history. It is lethal. It is now. And it has already entered its countdown phase.

Complicating Heat's mission to bring the rogue spy to justice and thwart the looming terror event, a serial killer begins menacing the Twentieth Precinct, and her homicide squad is under pressure to stop him, and soon. Known for his chilling stealth, the diabolical murderer not only singles out Nikki as the exclusive recipient of his taunting messages, he names her as his next victim.

From audible.com:

Richard Castle, New York Times mega-bestselling mystery writer and star of ABC's hit primetime show Castle, is back. In the seventh novel of his popular Nikki Heat series, the NYPD's top homicide detective has been promoted to captain just in time to face a thrilling case with a very personal twist. Captain Heat's fiancé, Pulitzer Prize-winning reporter Jameson Rook, is deep in an investigation. Professionally for Heat, Rook's meddling in the case compromises her new job. Privately, it becomes an early test of their engagement when Rook becomes a distraction at best, and an obstacle at worst, as their parallel lives not only cross but collide.

From amazon.com:

Hot on the heels of Richard Castle's #1 New York Times bestseller Heat Rises comes the fourth novel in the Nikki Heat series, Frozen Heat. Nikki Heat and Jameson Rook are together again, facing an unsolved murder mystery that has haunted Nikki for ten years. NYPD Homicide Detective Nikki Heat arrives at her latest crime scene to find an unidentified woman stabbed to death and stuffed inside a suitcase left on a Manhattan street. Nikki is in for a big shock when this new homicide connects to the unsolved murder of her own mother. Paired once again with her romantic and investigative partner, top journalist Jameson Rook, Heat works to solve the mystery of the body in the suitcase while she is forced to confront unexplored areas of her mother's background. Facing relentless danger as someone targets her for the next kill, Nikki's search will unearth painful family truths, expose a startling hidden life, and cause Nikki to reexamine her

From amazon.com:

Fast-paced and full of intrigue, Heat Rises pairs the tough and sexy NYPD Homicide Detective Nikki Heat with hotshot reporter Jameson Rook in New York Times bestselling author Richard Castle's most thrilling mystery yet.

The bizarre murder of a parish priest at a New York bondage club opens Nikki Heat's most thrilling and dangerous case so far, pitting her against New York's most vicious drug lord, an arrogant CIA contractor, and a shadowy death squad out to gun her down. And that is just the tip of an iceberg that leads to a dark conspiracy reaching all the way to the highest level of the NYPD.

But when she gets too close to the truth, Nikki finds herself disgraced, stripped of her badge, and out on her own as a target for killers with nobody she can trust. Except maybe the one man in her life who's not a cop. Reporter Jameson Rook.

In the midst of New York's coldest winter in a hundred years, there's one thing Nikki is determined to prove: Heat Rises.

From audible.com:

Nikki Heat and Derrick Storm, New York Times best-selling author Richard Castle's most enduring and beloved characters, team up for the first time to save Nikki's mother, Cynthia, who has been in hiding (and presumed dead) for 17 years. Standing in their way is a nefarious group of Chinese businessmen known as the Shanghai Seven, who have the resources - and ruthlessness - to stop them.

From audible.com:

The title character from ABC's hit television series Castle kicks off his new series of books featuring tough and sexy New York police detective Nikki Heat with a bang.

From audible.com:

An ISIS-style beheading of a journalist, carried out by a New York City group pledging fealty to that rogue state, becomes more than just another case for NYPD Captain Nikki Heat when the killers announce their next target: her husband, magazine writer Jameson Rook. Meanwhile, Heat is haunted by a fleeting glimpse of someone she swears is her mother, a woman who has been dead for nearly 20 years.

From amazon.com:

Nikki Heat and Jameson Rook are together again in Richard Castle’s thrilling follow-up to his New York Times bestseller, Heat Wave.

When New York’s most vicious gossip columnist, Cassidy Towne, is found dead, Heat uncovers a gallery of high profile suspects, all with compelling motives for killing the most feared muckraker in Manhattan.

Heat’s murder investigation is complicated by her surprise reunion with superstar magazine journalist Jameson Rook. In the wake of their recent breakup, Nikki would rather not deal with their raw emotional baggage. But the handsome, wise-cracking Pulitzer Prize-winning writer’s personal involvement in the case forces her to team up with Rook anyway. The residue of their unresolved romantic conflict and crackling sexual tension fills the air as Heat and Rook embark on a search for a killer among celebrities and mobsters, singers and hookers, pro athletes and shamed politicians.

This new, explosive case brings on the heat in the glittery world of secrets, cover-ups, and scandals.

From audible.com:

In New York Times best-selling author Richard Castle's newest novel, an illegal immigrant falls from the sky and NYPD Homicide Detective Nikki Heat's investigation into his death quickly captures the imagination of her boyfriend, the Pulitzer Prize-winning journalist Jameson Rook. When he decides to work the case with Heat as his next big story, Nikki is at first happy to have him ride along. Yes, she must endure Rook's usual wild conspiracy speculations and adolescent wisecracks, but after reuniting following his recent assignment abroad, she's glad for the entertainment, the chance to bounce ideas, and just to be close to him again and feel the old spark rekindle. But when Rook's inquiry concludes that Detective Heat has arrested the wrong man for the murder, everything changes.

Balancing her high stakes job with a complicated romance has been a challenge ever since Nikki fell for the famous reporter. Now, her relationship lurches from mere complexity into sharp conflict over the most high-risk case of her career. Set against the raging force of Hurricane Sandy as it pounds New York, Heat battles an ambitious powerbroker, fights a platoon of urban mercenaries, and clashes with the man she loves. Detective Heat knows her job is to solve murders. She just worries that solving this one will be the death of her relationship.