The prequel to The Davinci Code, Angels And Demons brings out the best in Dan Brown.
Our hero, Robert Langdon is summoned unexpectedly to help solve the murder of a respected priest and scientist by the name of Leonardo Vetra, regarding an ancient satanic cult called the Illuminati. A droplet of antimatter, the equivalent of a nuclear warhead has been stolen from the Vetra's lab and is being used to destroy Vatican City. As the city and the lifes of four cardinals are threatened, Langdon and Vetra's daughter, Vittoria join forces to find Vittoria's father's killer and save The Vatican.
Although Brown's writing isn't all that great and his books are written like movies, his masterful weaving of amazing and realistic plot-line is an artwork few can master, and yet with it he has produced four New York Time's #1 Bestsellers. If this isn't a true sign of a good writer, I don't know what is.
So if you're looking for an actionpacked, complex, realistic, long, entertaining novel, you know where to find it.