There comes a time in every hit man or woman’s life to hang up the garrotte and stow away the guns. The assassin protagonists of these books are understandably world- and work-weary, but old habits die hard when you’re a killer for hire.

It’s impossible not to like Billie, Mary Alice, Natalie and Helen, even if Deanna Raybourn’s Killers of a Certain Age makes it abundantly clear that the quartet could easily kill someone and get away with it if they so desired. After all, they’ve done just that many, many times during their 40-year careers as elite assassins for an international organization called the Museum.

The women are smart and funny, each with a specialty (poison, bombs, weapons) and all with extensive training in planning and carrying out assassinations. As Billie quips, “Our job is to eliminate people who need killing.” So it’s quite a shock when, before they’ve even had a chance to enjoy the all-expenses-paid retirement cruise arranged by the Museum, the women realize someone has decided that they need killing—someone who just might be on the board of their former employer. The women take a moment to indulge their anger like any longtime employee would (“We’ve given forty years to those assholes and this is how they repay us.”) and then surge into action, joining forces to figure out who’s after them and why.

Raybourn, an Edgar finalist and bestselling author of the Veronica Speedwell historical mystery series, has created a group of protagonists who are as reliably charming as they are impressively badass. It’s fascinating to follow along as they map out routes, create disguises, work their connections and improvise weapons. They handle it all with practiced aplomb, even if they occasionally groan with aggravation after battles to the death leave them feeling achier than they used to. But the four “avenging goddesses” are also able to use sexism and ageism to their strategic advantage, given that the combo renders them virtually invisible.

Ingenuity and instinct combine with deadly determination in this memorable thriller that celebrates friendship, ponders the meaning of loyalty, and offers plenty of action-packed entertainment among all the, well, killing.

In contrast to the ladies’ collaborative approach, there can only be one top-notch killer in the world of Seventeen. Screenwriter John Brownlow’s debut novel gives that number one spot to his brashly confident narrator, a man known only as Seventeen.

To achieve assassin supremacy, you must kill your predecessor—but Sixteen suddenly disappeared eight years ago. He’s the first assassin in 100 years to have done so, making Seventeen the only one who hasn’t truly earned his spot, according to his handler (who, of course, goes by “Handler”). Seventeen’s a consummate professional nonetheless, with a practical approach to his work: “I’m not saying what I do is a public service exactly, but actions have consequences.”

Now, though, it seems Seventeen himself may have begun to suffer the consequences of his chosen career path. After a multitarget assignment gets a bit messy, and he completes two subsequent jobs in Berlin without his usual finesse, he worries he might be losing his touch, and it seems like Handler might agree. When he informs Seventeen his next job is to find Sixteen and take him out, Seventeen’s hunch intensifies. Can he find and finish Sixteen before Handler sends someone else to finish him, too?

Brownlow’s snappy prose and brief chapters will have readers eagerly flipping the pages. Sixteen may be off the grid, but he’s not going to be off his game: He’s too smart to let his guard down, and he’s got 20 years of experience on Seventeen. As the ultimate showdown nears, compelling secondary characters add to the darkly humorous fun, intense action scenes amp up the suspense, and Seventeen reflects on the tragic childhood events that set him on his ruthless career path. That exploration of the far-ranging effects of trauma, as well as forays into geopolitics and governmental corruption, bolster the cleverly constructed, propulsive thrill ride that is Seventeen.