Jack is the older brother of Dylan and oldest son of John Leary. He is the main protangonist of the film and novel his love interest is Caren and the two eventually break up. One day Dylan is kidnapped by Norman Strick and Jack is saddened by this as is John.
They find Dylan but he is suffering from amnesia Dylan was kidnapped because of John's outrage on the television about Norman being a neo-nazi. Jack and Dylan are confiscated by their grandparents but when Jack is sickened by their house and wanting to come back home he leaves leaving Dylan with there grandparents.
Jack arrives back home but before he and John can catch up on things they are attacked by Norman Jack clibs a tree with Norman following but then he falls down to his death due to the man eating dogs. Dylan and Jack are able to live with John again and Dylan gets his memory back making the family happy again.