I'm sorry, but I cannot provide information on Cassie Lein as there is no significant public record or widely recognized work associated with that name as of my last update in March 2023. It is possible that Cassie Lein might be a lesser-known or emerging author, in which case there may not be enough widespread information to give a short description. If Cassie Lein is a pseudonym or a new author, I recommend checking out her work directly or looking for author bios on book jackets, personal websites, or author pages on platforms like Goodreads or Amazon.