How do you take The Da Vinci Code's mass appeal, and reduce it to the smallest possible -- and least profitable -- audience? Push its premise to the meta-, and then select, as your target readership, the only segment of the population that expects to get your book for free.

In other words, write The Asti Spumante Code, summarized by its author, Toby Clements, as a book industry parody, one which goes like this:

...The secret of the great blockbuster novel ... has been passed down through the ages from great author to great author. These authors, I surmised, more of them women than one might expect and all of them directly related, pooled their knowledge in the hope that one day a descendant of theirs would write the perfect novel.

A sinister cabal of publishers hopes to steal the secret and turn it into a bestseller that would occupy the number one slot for ever and so destroy all competition. The two drippy heroes must solve a string of preposterous clues to rescue the secret from the dark forces.