The Modigliani Scandal by Ken Follett (1976) from the free bin at my library, and I'd say it was worth just about that much.
The story focuses on a group of people who have all been put on the trail of a lost Modigliani painting. Our first protagonist, Dee Sleign, is looking for a topic for her thesis while she is vacationing in France with her rich older boyfriend. Her topic of interest is drug use and art. She goes to talk to an old man who used to know all the painters, and he clues her in to the surviving painting, although he doesn't really know where it is now and can only provide the vague clue of the name of a town in Italy. The thing that makes this particular painting even more exciting to the art world is that Modigliani painted it while he was high! On hashish!
Dee is so excited about this that she sends her uncle, the owner of an art gallery, a postcard with one sentence about her possible find. He gets so excited that he naturally puts a private detective on the case to get the painting before his niece does. Then, after finding another clue, Dee sends a postcard to her friend Samantha Winacre, a popular actress. She should really stop communicating through impulsive postcards. Julian Black, a failed artist and failing gallery owner who is emasculated by his wife and her family money, sees the postcard, and goes to Italy to try and get the painting for his gallery. Plus art forgery! Sex! Drugs! Sex! Money! Europe! Art!
Follett makes the mystery of the painting secondary to the machinations of all these shallow and unlikable characters who dance around each other in predictable and uninteresting ways. His commentary on the art world is very heavy-handed, and the sex and drugs, as well as the way the women are written, really date the book. This gave me a definite Jacqueline Susann feeling, but with all the fun and tawdriness taken out.
This is the only novel by Follett that I've read, and it was one of his first. He turned into a bestselling writer of thrillers, so this obviously isn't the one to judge him on. Follett himself says as much in the preface to this edition and on his website (which you should go to just to see the author picture in the banner).