Lexi Carmichael has a rule about animals: avoid them at all costs. But this time the cost is too high.

I’m supposed to be counting cards, raking in money, and celebrating Gwen’s bachelorette party in Atlantic City, New Jersey, preferably while my little black cloud stays home. I mean, who needs trouble when you put four accomplished women on a mission inside a casino? But nothing is ever easy for me.

It all started with a golden retriever who decided I’m her favorite piece of prime rib. Of course, I assume the universe is inconveniencing me once again. I have a long, complicated history with animals, and none of it ends well.

What begins as an awkward attempt to reunite a suspiciously brilliant dog with her owner soon spirals into something far more dangerous. Luckily, my fiercely loyal girlfriends—a CIA researcher, a very pregnant fashionista, and a giddy microbiologist planning the wedding of her dreams—and I are more than capable of handling ourselves as we unravel a scheme with scary technological and intelligence-community implications.

Turns out my little black cloud is thriving, because saving one very smart dog might expose a global scandal. But if we pull it off, we’ll protect national security, save a life that happens to have four legs, and prove—without even trying—that girls have way more fun than guys when left alone for a long weekend.