If you hear that the subject is the growing pains of a boy (William Eadie) in an infested slum during the 1970s Glasgow garbage collectors' strike, you may bolt from the theater, saying, "I gave at the office." Stay, all the way to the magical-tragical ending. Writer-director Ramsay neither sentimentalizes nor garishes up the lost children in this observant and poetic drama. She sees that kids aren't good or bad; they are exactly as weak, dreamy, vicious and stranded as the rest of us. Ratcatcher sears; it is hard to take, hard to shake.