Shadow Days is a great prequel to Nightshade. This novella is 84 pages and contains a lot of information regarding Shay and his past. Ms. Cremer continues to amaze me with her imagery and character building. This novella allows readers to become more familiar with Shay and who he is/was before attending the Mountain School. Nightshade begins right where Shadow Days ends so readers are not going to miss anything. If you haven't read Nightshade yet, then I suggest starting with this fantastic prequel. If you have read Nightshade but missed out on this, then I recommend you read it anyway. It is a great story and it is from Shay's POV so you gain more of an understanding about him and his relationship with his Uncle Bosque. It is not repetitive to anything in Nightshade, although some situaions are briefly mentioned in the novel to provide a background.
Please visit this site to read Shadow Days and for information regarding the Nightshade series and Andrea Cremer. There are also several videos featuring Shay as well as the nightshade trailer.
Feel free to leave comments, questions, suggestions, and recommendations in the comment section. =)