Prime Video's 56 Days threw in a surprise twist - and some book changes - that shifted the trajectory of the show. Based on Catherine Ryan Howard's novel of the same name, 56 Days follows couple Oliver (Avan Jogia) and Ciara (Dove Cameron) as they start an intense relationship after meeting in a supermarket. Their romance is questioned after an unidentifiable body is found in a bathtub. In addition to Jogia and Cameron, Megan Peta Hill, Dorian Missick, Karla Souza, Patch Darragh, Kira Guloien and Celeste Oliva make up the cast.