I've rewatched these episodes in the order used by seemingly everyone other than IMDb, where this is Episode 19. I don't think it makes much difference in narrative terms, just in statistics.
One statistic that's unchanged is I believe this is the first episode where the villain is an old friend of MacLeod's. This isn't exactly a twist: The first scene involves said villain, Gabriel Piton, an Immortal fashion designer obsessed with beauty, murdering his young lover after she discovers his cache of hidden art treasures. And it's debatable how much of a friend he was: The flashbacks show him as a hedonistic thief that Duncan had already begun to tire with, and in the present day he doesn't seem to feel anything other than discomfort at their reunion. He shows very little reaction at Richie dubbing his old friend a murderer so his extreme reaction near the end doesn't entirely ring true.
Richie decides to take on Piton after the latest young woman to catch his eye falls into the sociopath's orbit. Duncan mainly seems concerned with keeping Richie out of trouble (there's a few hints about the young man's future), and tries to cut a deal with Piton which unfortunately isn't quite tight enough.
Unfortunately, the episode drags a bit at times. There's a lengthy sequence of Richie pretending to be a blind man to steal a gun for what turns out to be an obvious set-up. A shame because his first confrontation with Piton is quite dynamic. Tessa is largely wasted again, but there's a nice friendship scene between Duncan and Richie to go out on.
French actor Oliver Pierre has a lovely small role as a waiter. Ironically, on the weekend I typed this, I caught him in an old episode of Lovejoy, while others may remember him as the original General Calvet in Sharpe.