Sylvie Montague is a gemologist called to Scotland to help the police catalogue the jewelry stash of a murdered drug runner. After arriving in Scotland, and after making dinner plans with a Mr. Tall-Dark-and-Handsome from the plane, Sylvie finds that her carry-on bag has been switched. The bag in her possession contains a mysterious stolen Romanian diamond called Katerina's Blood, a diamond that apparently belonged to the murdered drug runner.
Sylvie finds a smeared address but legible phone number on the luggage tag on the errant bag and calls the number. The voice on the answering machine that picks up is that of an old friend and former love, Paul Maigny. Paul is a collecter and has wanted this particular hunk of compressed carbon for a long time. Sylvie is really confused.
But since Sylvie has a hot date, she tucks the 80 carat rock into her bra and off she goes. Mr. TDaH turns out to be the jewel thief himself, Luca Colceriu. Luca tells Sylvie that Paul hired him to steal the diamond, but he doesn't intend to give it to Paul. Luca is Romanian, and he wants to return the diamond to his country "for his family's honor." He (Luca) is afraid to touch the diamond because legend has it that the diamond is cursed. Since Sylvie doesn't believe in curses (he knows this how?), he wants her to help him return it to Romania. I guess he can't wear gloves and buy a plane ticket.
Sylvie is intrigued and attracted. However, other people want the diamond as well, and soon Sylvie and Luca are chased across the Scottish landscape from town to town. After some slightly kinky foreplay, Luca takes off with the diamond. Sylvie turns to Paul, and eventually the entire plot is revealed.