Delta: Retribution by Cristin Harber is a fantastic military romance. Ms. Harber has delivered a book that is well-written and loaded it with phenomenal characters. Trace is mess after his twin is killed in combat. Marlena is a student and science whiz and is working on a secret project for the government. Trace and Marlena's story is loaded with drama, action, sizzle, suspense and a bit of humor. I totally enjoyed reading Delta: Retribution and look forward to reading more from Cristin Harber soon. Delta: Retribution is book 1 of the Delta Series but can be read as a standalone. This is a complete book, not a cliff-hanger.