They're mutated turtles and teenagers and ninjas, and New York City's subterranean avengers are back, matching some wits and a lot of weaponry against a bad dude known as Shredder. Jonathan Liebesman's re-boot of the popular comics-movie-TV-videogame-bedsheet franchise is unnecessary: (1) There have been four TMNT films already, and (2) How many evil-fighting superheroes can we possibly keep track of this summer? The plot, even including backstory for the uninitiated, could be written on the back of a matchbook, and it's padded with lots of CGI-heavy action, including a tumble down an epically tall snow-covered mountain within sewer-line distance of New York City. The turtles are well animated, which is more than one can say for their tedious human co-stars Megan Fox, Will Arnett and William Fichtner. See it only if your heart still belongs to TMNT, no matter what.