The books in The Dark Passage Series retail for $14.99 each in trade paperback, and $2.99 each for Kindle/E-Book. You can get a free audiobook with a free Audible trial.
Trade Paperbacks: Amazon | Barnes & Noble | Apple Books – Kindle: Amazon Kindle
E-Books: The Dark Truth | The Dark Descent | The Dark Terror
iTunes: Apple Books
Audiobooks: The Dark Truth: Audible | Apple – The Dark Descent: Audible | Apple
Indie Stores and Other Retailers (you can order online):
The Strand (NYC)|Powell’s City of Books (Portland, Oregon) | Bookshop.org | BAM! Books-a-Million | Lift Bridge (Brockport, New York) | The Last Bookstore (Los Angeles) | East Bay Booksellers (Oakland) | Green Apple Books (San Francisco) | Alexander Book Co. (San Francisco) | Parnassus Books (Nashville) | Books Inc. (Alameda, California)
Trade paperbacks are also available at Barnes & Noble locations in Modesto, Dublin, Arden Fair (Sacramento), Antioch and Concord, California.