Assault on Black Keep

From the introduction: Assault on Black Keep is intended for four characters with an average party level (APL) of 11. Characters who complete this adventure should earn enough experience to reach halfway to 12th-level. An undead horde is coming, and only the characters can stop it. The campaign takes place in Arden, although it can be set in your own world. Any party composition should be able to finish the adventure with intelligent play.