Rod Marquardt, author of Keller's Den, is alleging that King's novel, Duma Key, contains infringing content. He's asking for an injunction, destruction of copies, damages, and restitution.
The complaint is here. The entire cause of action seems to be that Marquardt published his novel in 2002, and King published his in 2008. The list of allegedly infringing content makes for very sad reading.