Namaste.
Question - Have you read the book "The Girl on the Train" by Paula Hawkins?
Question again - Did you like it?
If your answer to both question is yes, then it has nothing to do with the second book by the author i.e. Into the Water. In the book (and many other famous reviews) you will read that if you liked the first book then you would definitely like the second one.
THAT IS TOTALLY NOT THE CASE.
Read why -