I remember the Moon-Spinners, from the movie starring Hayley Mills (the story differs a little from the book) and recently found the book by Mary Stewart who died last year at the age of 97.
In the Moon-Spinners, Nicola has planned to meet her cousin at a small coastal hotel on the Greek island, Crete, but on her way there, Nicola comes across an injured man and tries to help him. What she doesn't realize is that his injuries are no accident and she finds herself among ruthless criminals who are hiding out in the small Greek village. As is common in books written in the 60s, the story is a little long winded at times and much repetition, but it's a good mystery and Mary Stewart's descriptions are delightful.