() Naked Heat (September 28, 2010) () Heat Rises (September 20, 2011) () Frozen Heat (September 11, 2012) () Deadly Heat (September 17, 2013) () Raging Heat (September 16, 2014) () Driving Heat (September 15, 2015) () High Heat (October 25, 2016) () Heat Storm (May 2, 2017) () Crashing Heat (Mar 12, 2019) () Nikki Heat fictional characters Detective Nikki Heat is loosely based on NYPD detective Kate Beckett, with a similar backstory. Her decision to become a detective was motivated by the death of someone close to her – although Heat has a niece and siblings that Beckett lacks – and the first case she investigates is adapted from several real cases Castle helped Beckett solve. Heat is assisted by sometimes-lover journalist Jameson Rook, and colleagues, Detectives Raley and Ochoa. Originally a theater major at Northeastern University, Nikki switched her major to criminal justice after her mother's murder. She is a practitioner of Brazilian jiu-jitsu, and often spars with Don, her Navy SEAL combat trainer-with-benefits until his murder in Frozen Heat. Nikki carries the NYPD-issue SIG-Sauer P226 DAO as her duty weapon (unlike Beckett, who uses the Glock 19). She lives at an apartment in the Gramercy Park neighborhood of Manhattan. At the end of Raging Heat, Rook proposes, and the two are married in the epilogue of Driving Heat by their friend and frequent poker buddy, Judge Horace Simpson. In Frozen Heat, Nikki learns that her murdered mother, Cynthia Heat (née Trope), was a CIA agent who worked as a piano tutor for the children of various foreign nationals, and that she was murdered because she had uncovered a terrorist plot. After ten years, Nikki was able to close the case and bring her mother's killer to justice. Although Nikki passes the Lieutenant's exam with flying colors in Heat Rises, she declines the promotion in order to remain a homicide detective. She is promoted to captain of the 20th Precinct in Raging Heat after the death of Captain Wallace Irons. Although she had a little bit of a rough start as Precinct Commander in Driving Heat, Nikki eventually finds her footing. It is mentioned in High Heat that Nikki has spent her entire career at the 20th, first as a rookie beat cop, then as a patrol sergeant, followed by detective and detective squad leader, and culminating in her current rank as captain. Nikki and Rook also