56 Days, Prime Video’s new murder mystery thriller based on Catherine Ryan Howard’s bestselling novel, is the TV version of a forgettable fling. On first impression it’s exciting, or at least intriguing enough to convince you to come back for a second date, maybe a third. But the longer you stick around, the more you start to suspect there’s not much there there. It’s a pretty face in slick outfits, charming enough to distract you for a little while, but ultimately just parroting the same old lines you’ve heard a million times already. 56 Days The Bottom Line Not enough heat and not enough warmth. Airdate: Wednesday, Feb. 18 (Amazon)Cast: Dove Cameron, Avan Jogia, Karla Souza, Dorian Crossmond Missick, Megan Peta Hill, Alfredo Narciso, Dylan Colton, Patch DarraghCreators: Lisa Zwerling, Karyn Usher, based on the novel by Catherine Ryan Howard For a while, however, the sheer grossness of its central mystery is enough to lure in some interest. By the time the police have been called in to investigate an unidentified body in a luxury …