Ah, women-in-prison and Jesus Franco. What can we expect.
It really depends on the version you watch, as there are versions from 70 minutes (UK) to 99 minutes (Argentina). The US and Sweden have 86 minute versions, although Sweden banned even that. This is a 90 minute unrated version.
One does not expect to find a double Golden Globe and Oscar winner in a Jesus Franco film, but here she is - Mercedes McCambridge (All the King's Men - 1949) as the prison superintendent.
Also Maria Schell, who has 2 BAFTA Film Award nominations and another 14 awards, as an inspector from the Ministry. She did get prisoner 99 (Maria Rohm) out of solitary on her first day.
More expected is Herbert Lom as the Governor, the only surviving member of The Ladykillers (1955), and a Razzie nominee for King Solomon's Mines.
It appears Franco was going for quality as it is more than a half hour in before we see a breast, and some girl-on-girl action. Even that was shot with a lot of Vaseline on the camera. Don't the women in this prison take showers? Marie (99), Zoe (Rosalba Neri), and Rosalie (Valentina Godoy) attempt to cross 30 miles of snake-infested jungle and swamp at night to escape. yeah, right. They find a lily-covered pond that looks the same as the one in Virgin among the Living Dead.
Of course, it isn't the snakes on the ground they have to worry about, but the snakes attached to the dozen male prisoners that saw them and are running after them. One doesn't make it.
A good drama with some famous actors, but disappointing as a WIP exploitations.