At first, this movie seems like its taking the same well-trodden path as such films at “The Principal.” You know: new teacher arrives at run-down high school populated by aggressive, undisciplined youth, and he shows them a thing or two so that they finally learn some respect. But “Detention” takes a page from Roger Corman exploitation movies, and crosses that line in the sand to go where no high school film has gone before to enter a lurid, B-movie nether-zone involving kidnapping, electroshock behavior control, and a new, particularly painful form of torture that centers around playing Tony Basil’s “Mickey” over, and over, and over again.