Just because a woman hits 60, it doesn’t mean she’s weak or powerless. And the women of Killers of a Certain Age are here to make sure we don’t forget it!

In this action-rich thriller by the talented Deanna Raybourn, the four women at the heart of the story should be enjoying the celebratory luxury cruise marking their retirement — but when they spot a fellow assassin from the shadowy organization they work for hidden among the ship’s crew, they realize they’ve been targeted, and soon enter a fight for their lives.

As the foursome evade death through all sorts of clever, daring, inventive means, they know that the kill order must have come from the top, and in their world, as the blurb says, it’s kill or be killed. Banding together, they plot, scheme, and fight to take out the Museum’s Directors. With their own lives on the line, one mistake could mean the end for all of them.

Killers of a Certain Age is a fast-paced adventure, with the four main character at its heart using their mad skills, cunning, and whatever tools they have at hand to turn their own assassinations back on their adversaries and, they hope, finally leave the business behind them for good.

Each woman is given a backstory, although some are more fleshed out than others. The Museum, we’re told, was originally founded in the aftermath of the second World War, with the purpose of finding and eliminating the many Nazis who managed to slink away and evade justice. Over the years, the Museum’s mission expanded to include drug lords and criminal masterminds. Unaffiliated and uncontrolled by any one government, the Museum is a well-funded, top secret, highly powerful organization that moves through the world via stealth and surveillance, and takes out those deemed the highest threats.

Now, to enjoy Killers of a Certain Age, we readers have to put aside any qualms about the morality of an extra-legal assassination organization. We’re clearly meant to root for Billie, Mary Ann, Helen, and Natalie, and to understand that they see themselves as forces of good. Yes, they clean up the rot that pervades the world and evades more traditional types of justice. But at the end of the day, they’re women who’ve spent 40 years traveling the world and murdering people. I can’t bring myself to feel sorry about them dispensing justice to Nazis and cartel bosses… but I can’t say I’m entirely comfortable with this either.

Still, accepting that these are our heroines, it’s certainly fun to cheer for their success, especially when they take advantage of other people’s views of older women to be able to slip into places unseen and unchallenged.

There are some funny moments (such as the women using a menopause-tracking app with animated kitten avatars as a way to communicate without being tracked), but overall, it’s not a particularly funny book (which readers coming from the world of the author’s Veronica Speedwell mystery series may be expecting). The characters are memorable, and I loved reading a story where women “of a certain age” not only matter, but truly kick ass, take names, and make a difference.

The underlying concept — four assassins as the heroes of a story — still doesn’t sit entirely well with me, but overall, this is a fun, fast, exciting read. Kind of like a female James Bond squad, but with murder. If you don’t take it too seriously and just go with the concept, it works!