“In Secret” might have been a much better film had the filmmakers acted as boldly as the characters. Based on Emile Zola’s 1867 novel “Thérèse Raquin” and the play of the same name, “In Secret” tells the sordid tale of Thérèse (Elizabeth Olsen), whose father forces her to live with her aunt, Madame Raquin (Jessica Lange), and her cousin, Camille (Tom Felton), after her mother dies. Thérèse essentially becomes nurse and maid to the ever sickly Camille.