Jane and Dan at the End of the World by Colleen Oakley

 Jane and Dan have been married for either 19 or 20 years, depending on which one you ask. Jane thinks Dan is having an affair plus she wants a change. So during their anniversary dinner at the the very expensive, very inconveniently located Fin du Monde (end of the world) restaurant, she announces that she wants a divorce. Before they can discuss it, a group of armed activitists storms into the restaurant and ties everyone up. Their plan is to get millions of dollars from one of the weathiest men on earth, Otto, who is supposed to be dining there with his family. But oops, he's not there yet. So begins a long wait. 

Jane soon realizes that the activists are following the plot (and using some of the dialog) from a book she had written 6 years earlier. And she knows that the book doesn't end well for the hostages. But she can't convince Dan she's right until even he starts recognizing events from her book. 

Jane and Dan's relationship can be summed up in the scene where she's trying to mouth to him across the room to get the WiFi password from the chef (who is next to Dan) so they can summon help.  First he thinks she's saying "Get the fast food." So he asks her if she's hungry. She in frustration tries again. Now he think's she's saying "Hit the bathroom." Needless to say, she never does get the WiFi password. Dan does, however, redeem himself later when he takes out one of the terrorists using a skill Jane didn't know he possessed.

The book is an interesting mix of tension (Will these activitists shoot them? Is there a bomb in the restaurant?) and sly humor. I found it totally entertaining.