Who Will Publish Your Book?
Okay, so let's assume that the author files a lawsuit. Your publisher -- assuming you were lucky enough to find one in these troublesome days of publishing -- (or your publisher's insurer) would likely ask you to pay the costs of the lawsuit based on the indemnity provision in your contract. So even if you win the lawsuit -- or you settle as they did in this case -- you probably will have given up most of your royalties to pay the attorneys. And if you lose the lawsuit, -- as in this case -- then you pay the attorneys, and your book goes unpublished.
Can You Win The Lawsuit?
Okay, now for the fine print. Is it legally permissible to borrow? Maybe. Some plots -- boy meets girl, boy loses girl, boy gets girl -- and some characters -- good cop, bad cop -- are so stock, that they are considered merely "ideas," not original expressions -- a theory best expressed in this case. In other cases, the author may create something transformative that qualifies as a fair use. (Keep in mind these are issues raised at trial, so the attorney is billing as you prove your point.) There are many cases on the subject of borrowing plot and characters and you may want to peruse a copyright treatise before penning your opus. And of course, as always, disregard all of the legal blather, above, if the book or character you are copying -- for example, Sherlock Holmes -- is in the public domain.