CONTAINS BIG SPOILERS AND WATERING OF EYES
I don't know if it's something in the water, or hypnotic trance rays beamed at us from the solar system, but there suddenly seems to be a rash of movies in which guys get their genitals hacked off. Not only were there several occurrences of lovingly detailed deknobbings at FrightFest (Dream Home, I Spit On Your Grave, Wound), but I get home and find this seedy little entry with a castration sequence that differs from the standard eunuchisation process in just one respect.
Penance is actually a reimagining of Pete Walker's grubby British sleaze classic House Of Whipcord, in which a mad judge incarcerates promiscuous women in his own private prison to punish them for their wanton ways. Here it's an insane gynaecologist, and the techniques he uses are far more sadistic and cruel than Whipcord's. Amelia, a young mother with cashflow problems, starts working as a stripper, and is promptly hired for a "private performance" - ending up locked away in an abandoned asylum with several other Women Of Fleshy Pleasures.
First off, it's yet another "found footage" job, apparently consisting of footage shot by Amelia's best friend (yet her captors seemingly allow her to keep the camera) intercut with footage shot by the torturers. Is everybody filming everybody else these days? Is nobody actually spending their lives without having a documentary made about them? (Incidentally, who's filming me, and who am I supposed to be filming?) Quite why the bad guys are capturing all this on tape eludes me. There's a suggestion that Amelia is filming these events because they're evidence, but given that her captors are also filming it, she really doesn't need to bother. I guess you don't need two camera angles of a woman having her labia and clitoris removed.
It's got a few medium-sized names in cameo roles - Michael Rooker, Tony Todd, Jason Connery, and the head maniac is Graham McTavish, the warden from Red Dwarf Series 8. McTavish is the guys whose nuts are removed, and that scene is interesting for two reasons:  because it serves absolutely no purpose, and  it's self-inflicted. Yup, he anaesthetises himself in an ice bath, sits down in front of the video camera (mercifully positioned slightly too high) and reaches for the garden shears and starts hacking away. Then drops his balls, and attendant tubes and veins, in a glass jar and stitches himself back up. For No Reason At All. Congratulations on your nut job, you nutjob. It's horrible, and not particularly well made, but the occasional bits of particularly horrible sadism perk the interest just enough to get it the second star. Just.