Summer Cruise, Summer Love

Totally unbelievable villains mar this pleasant vacation/adventure novel in which Kirstie Allen and her twin brother, Lance, accompany a wealthy friend on a summer cruise through the Greek islands. The three teenagers and their new friend Nicolas (the ship captain's son and Kirstie's budding love interest) foil international jewel thieves who attempt to plant diamonds in Kirstie's possessions in order to smuggle the stolen gems out of Europe.