The map of castle Avernus is not included.
An there isn't an alternative.
From the Shadows is a classic adventure and this is a very nice OCR scan of the module. However, the Castle Avernus maps critical to the adventure are not included.
You can find somewhat usable Avernus maps over at: http://www.fraternityofshadows.com/GryphonHill/darkon/avernus.html