Castle is seeking an actress to come on board for at least one episode this fall... and royally piss off all viewers!

According to an ABC casting notice, the series will feature a "gorgeous, sexy, sophisticated art insurance investigator," with the potential to recur, who is hiding a secret and who also sets her sights on a certain author.

What will this mean for Kate and Castle? It's unclear.

Who should take on this role? Let your opinion be heard now!