7th Sea, from AEG, the company behind Legend of the Five Rings. It's incredibly hard to find a print copy of, since I believe there were only 1 or 2 print runs. You can download a PDF from drivethrurpg for about $12 though.
They also made a d20 version called Swashbuckling Adventures, which I don't think was particularly well recieved, and still probably hard to find.