Jim Caviezel will play a dark mystery man in “Unknown,” an independently financed thriller that starts filming later this month under director Simon Brand.Caviezel will star with Greg Kinnear, Joe Pantoliano, Bridget Moynahan, Jeremy Sisto and Peter Stormare. Plot is being kept under wraps, but the drama is likened to “Memento” in that participants and viewers don’t know until the end who the bad guy is. Pic was scripted by Darby Parker and Matt Waynee; Parker is producing with Rick Lashbrook and John S. Schwartz. GreeneStreet Films Intl. is handling foreign sales, while ICM will broker the domestic deal. Brand makes his feature directing debut from the video and commercials trade.