In Linda Fairstein’s 2013 book Death Angel, Alexandra (Coop) Cooper and detective Mike Chapman finally get cozy and share a kiss atop Central Park’s Arsenal building on a beautiful June evening. This is after 10 years of camaraderie, crime-solving and electrified banter that barely hid their true feelings for each other, plus numerous best sellers by the Chilmark summer resident.

Fast forward to the start of Terminal City, Ms. Fairstein’s latest book. Mike Chapman has been gone for seven weeks, first on leave from the department for a relationship with a judge, and then on a trip to visit family in Ireland. Alex is looking forward to the romantic reunion. However, the body of a young woman is found at Manhattan’s famed Waldorf-Astoria Hotel. The crime seems to fall squarely under Alex’s purview as head of the Special Victims Unit at the district attorney’s office. The clock is ticking, though, as the president of the United States will take up residence at the hotel while attending a special session at the nearby United Nations. Alex Cooper, Mike Chapman and detective Mercer Wallace have just 48 hours to solve the crime.

Two more victims, both with their throats slashed identically to that of the woman found at the Waldorf, are then discovered. Tying them together is a distinct design resembling train tracks that has been branded onto their skin, plus the close proximity of the crime scenes to one of New York city’s most iconic landmarks: Grand Central Terminal.

Ms. Fairstein, a Chilmark summer resident, continues to publish a book a year.

Accompanied by some of the finest officers and engineers from the NYPD and Metro-North, Alex, Mike and Mercer prowl the secret tunnels and passageways of the world’s sixth most visited tourist attraction. Their search brings encounters with homeless “mole people” dwelling in abandoned track tunnels beneath the station, employees dedicated to moving thousands of people through the station each day, and some unwilling accessories to the crime who are reluctant to give any information to the police.

Finally, a victim’s roommate offers clues about the killer’s motives, and science prevails in the form of a DNA match. When the police and our heroes finally catch up with the killer, Grand Central Terminal is put under lockdown for the night. The action plays out in scenes of tense stand-offs, gunfire and blackouts.

A hallmark of Ms. Fairstein’s thrillers is her incorporation of facts and history about the New York city landmarks that play such a large role in her narratives. In Terminal City, the reader learns about the celestial design for the Great Hall in the Grand Central Terminal that was misinterpreted by its painters in 1913, the secret track built to accommodate President Roosevelt’s armored train, and the revelation that the station was sold into private hands for $80 million in 2006. Ms. Fairstein also gives a nod to longtime Vineyard resident Jacqueline Kennedy Onassis, who helped spearhead the restoration of the terminal when it was slated for demolition.

Terminal City is Number 16 in Ms. Fairstein’s Alex Cooper series. Ms. Fairstein continues to publish a book each year, and keeps her plots fresh through personal intrigue, but also by following the headlines. Terminal City co-opts New York city’s “Cannibal Cop” case, which resulted in the conviction of a NYC police officer just six months ago. Ms. Fairstein also fearlessly invokes the already tempestuous reign of New York city’s recently elected mayor by referring to Bill De Blasio’s campaign slogan “Tale of Two Cities.” She also takes on the snow plowing issues of 2014, and the dismissal of a controversial civil lawsuit pertaining to the NYPD’s profiling practices.

Despite the murders, the danger of tunnels located 10 feet below Grand Central and the possibility of a terrorist attack on Manhattan, the real engine of this book is personal. The possibility of Coop and Chapman’s romance hangs over the story like the thick August heat in which they are working. Underneath Chapman’s bristly needling of Alex, and her own sassy banter and one-upmanship, it has long been clear that they care deeply for each other. And when danger is close by, they will always have each other’s back. But this time around, there’s sexual tension and emotional danger.

By the close of Terminal City, it still doesn’t look as though Alex will get to the Vineyard with Mike for oysters and lobster at the Bite during August. An escaped felon is still on the loose, with the words “Kill Coop” tattooed across his knuckles. But we’ll have to wait until next June to find out what Ms. Fairstein holds in mind for our heroine’s future.

Linda Fairstein will hold book signings at Bunch of Grapes on July 4 and Edgartown Books on August 7.