The cover of this says "thriller" and I was expecting a crime novel because I was a huge fan of Ginsburg's last, excellent one SUNSET CITY. But the summary is correct on this one, it isn't really a thriller. It's barely a crime novel, at best the crime is the B plot, and besides a quick prologue you don't even get back to it until nearly halfway through the book. It's also much too slowly paced to be a thriller so I'd suggest adjusting your expectations to the summary rather than the cover.
Ava, newly orphaned, is sent to live with Lane, a grandmother she doesn't know. Lane is an artist in New Orleans, eccentric and prickly, and also in the grips of a growing dementia. Oliver is technically Lane's assistant, but he is more often her drinking and smoking buddy, and Ava's arrival upsets all of their routines. For Ava, it's a rude awakening from her orderly childhood to a house where no one seems to act like an adult. The crime is an old one that at first seems barely connected to the present situation, but gradually becomes all-encompassing.
This is basically lit fic. It has the very slow pace, the focus on character and setting. It also has a slightly unusual narration, third person omniscient, but it sometimes shifts from one character to another in the middle of a scene. It is about art and grieving with plenty of coming-of-age thrown in. And yes there is a crime that ends up being at the center of the story, but that's true of plenty of literary novels that we wouldn't classify as crime fiction so I think it's best we put it there.
For me, this didn't quite work because I never quite got the characters. On the surface it all made sense but as we dived deeper I just couldn't connect with them more fully. Lane is the best written of them, the prose moves very well through the jumping thoughts of her mind pulling her from one time to another. I very much relate to Ava but she is so thoroughly put together through all of this, even if that is true to character it didn't feel true to her internal life. And Oliver kept doing things that made no sense to me, especially near the end. I'd hoped this could build to something, but it never quite did. And the journey along the way didn't hold my interest as well as I would have liked.