By Clea Simon

Through it all, Deanna Raybourn’s quartet of females rely on the acuity and resourcefulness that has made the author’s other series characters both so memorable and beloved.

Kills Well With Others by Deanna Raybourn. Berkley, 368 pp., $29

A little creaky, but still competent, the professional assassins of Kills Well with Others are showing their age. The four women, recruited in their youth by a clandestine operation known only as the Museum, are ready for retirement. As likely to disguise themselves as Depends-wearing Bingo players as Playboy Bunnies, they would prefer to give up the guns, knives, and martial arts they mastered decades ago. But when one of their own is taken out in apparent retaliation for a years-old hit and the quartet realize that they themselves are targets, they rally, once again, with thrilling results.

If this sounds a bit close to the plot of Killers of a Certain Age, author Deanna Raybourn’s first outing with her assassins Billie, Helen, Mary Alice, and Natalie, it is. In that Barry-winning blockbuster, the team really was celebrating retirement from the Museum, a World War II relic that has taken on itself the duty of ridding the world of heinous criminals. Until, they realized, someone had interpreted “retirement” as something other than a leisurely cruise, sparking a life-or-death struggle that called on years of training and strained some aging muscles in the process. It was fast, furious, hilariously funny, and, one might think, a one-off.

Raybourn, after all, made her name (and was nominated for a Mystery Writers of America Edgar Award) writing enjoyable, fast-moving historical mysteries, featuring protagonists like Veronica Speedwell, a Victorian lepidopterist who bent the prevailing social norms to her will, a resourceful proto-feminist with the skills, learning, and most of all wit to solve crimes and generally embrace life. Venturing into contemporary times, and with heroines who more accurately reflect the peer group of the 56-year-old author and, one assumes, many of her readers, was a leap — one Raybourn landed perfectly.

A second book was always going to be a challenge. But if Kills Well With Others lacks the freshness of Killers of a Certain Age, the novel makes up for it with complex plotting that mixes past and present-day timelines, giving us insight into the Museum and making our protagonists work a little harder than previously, testing their stiff joints and even stiffer preconceptions.

It all starts off with a botched hit more than 40 years ago. The four are undercover as Playboy Bunnies, a role that fits the buxom and gorgeous Mary Alice more than her colleagues. The target is the nephew of a Toronto gangster, an “ambitious” thug who is pushing his crime family into drugs and underage prostitution. “He likes violence for its own sake,” they have been told, and thus he becomes a target for one of the Museum’s ethical hits. Frustrated, Billie, who once again serves as the book’s main voice, always cynical and up to the job, takes the lead. However, when the assignment goes off track and Billie’s attempt to correct it only makes the matter worse, she and her colleagues run afoul of the Museum — and some very dangerous people.

When we switch to the present day and hear of the death of a member of the Museum’s Provenance department, the section that investigates possible targets, logic dictates that both their Museum handler and the quartet themselves reevaluate cases the dead Lilian Flanders had worked on. Along the way, Billie finds herself recalling yet another old case, one that she completed — leaving a corpse in a pyramid for the jackals to find — but which was never fully resolved.

That’s a lot of old bodies that may want avenging. But it isn’t only the killers out there who are giving the crew trouble. By their age, the four have acquired partners and with them all the baggage relationships bring. Widowed Helen, who has been bereft, may be falling in love again, in stark contrast with Natalie, who “dabbled in performance art” with “a number of gallery shows, and the same number of ex-husbands.” Mary Alice has found happy domesticity with her wife Akiko and their cats Kevin and Gary, but those connections weigh heavily on her professional responsibilities. Billie herself has no such meddlesome entanglements: her decades-long on-again, off-again relationship with the dashing Taverner is something she can leave at a moment’s notice. And does, when the news of Flanders’s murder spurs the team into action. But those attachments will complicate matters as the four begin their dangerous dance — both stalking and eluding their adversary on an adventure that takes them from England to Venice to the mountains of Montenegro.

Through it all, Raybourn’s characters rely on the acuity and resourcefulness that has made the author’s other series characters both so memorable and beloved. An older woman’s version of Ian Fleming’s James Bond novels, perhaps — with somewhat less sex but more believable violence. Billie, in particular, shines in this outing, coming to terms with the history that has made her so perfect for this job but, perhaps, less so for life. A history that has made her, in her mentor’s words, “a necessary monster.” And a good model for these days, perhaps. At least in our dreams.

Clea Simon is the Somerville-based author of 32 mysteries, most recently The Butterfly Trap.