Thicker than Water by Ashe Barker

Even as she pleads for her freedom, she hopes he will never let her go…
Determined to rescue her younger sister who is incarcerated in a foreign land, Jenna Ferris hatches a desperate plan. She sneaks into the small Arab state on a false passport, and even manages to gain access undetected into the royal palace itself.
So far so good. What can go wrong?
Everything!
Captured by the military police, she finds herself in a cold, stark cell, at the mercy of none other than the brother of the crown prince himself. She soon learns that Zafar Nur al-Talat has his own unique methods of interrogation, combining pain and pleasure to devastating effect. Before long, Jenna finds herself screaming for him to stop, whilst silently begging for more!
Powerful, handsome, ruthlessly determined, Zafar is sworn to protect his country. His English prisoner is beautiful, and he cannot deny his attraction to her, but she is hiding something and the security and safety of those he loves is at stake.
He will do his duty, which means he will discover the truth, whatever it takes.