Complex sentence: They are two six year juniors at Tommy's school who are large and unintelligent and often try to capture "The Pleasentville Werewolf," not knowing that they're actually chasing Tommy.
Split into simpler sentences: They are two six year juniors at Tommy's school who are large and unintelligent. They often try to capture "The Pleasentville Werewolf," not knowing that they're actually chasing Tommy.