Trouble in Marrakesh

Interpol has requested that Millie appear in Marrakesh, Morocco, at an International Tribunal to testify against the seemly harmless scoundrel they met aboard their first cruise. They soon learn that they and Ferdinand Modesto are in deeper trouble than they ever dreamed.
Joined by her sister Abby, the two are challenged at every turn of their travels. They come face-to-face with an explosion, being taken in for questioning by local authorities, a kidnapping, murder and a phantom-criminal known as Balthazar, all while Millie and Abby endeavor to do the right thing, but will they prevail?