The Woman in Cabin 10

So, this is basically The Girl on the Train... on a boat.

There are too many throwaway red herrings that are not explained. Perhaps the most unbelievable part is that Lo and/or her colleague and ex-boyfriend, Ben, are aspiring “investigative journalists”. I don't think these two could find their way out of a paper bag (after Lo has imbibed whatever alcohol was in said bag).

Only one way to read this one: suspend your disbelief and don't think about the answers you're given.