Chains of Shame by Brigitte Markham

As innocent but cheeky teenagers Laura and Helen enjoy the sun-drenched beaches of Corfu, Helen's aunt, Angela, has a novel agenda for them - she wants to oversee their sexual awakening. She finds them keen to experiment with their new discoveries; eager to be oiled and depilated; to explore their lesbian lusts; and to be introduced into the dark arenas of punishment and bondage. They are taken on to the private island of the perverse Mr Tostides, where their introduction to the sophisticated rituals of submission and domination can remain uninterrupted. Being a slave on Mr Tostides' island involves more than the girls had bargained for, however. Can they hope to escape before it is too late?