The whole movie plot relies on a very unlikely assumption: that the ex-husband would not visit Kidman at her mental institution where he put her in, nor call for any news at all, for four whole years... Even though divorced, they still share a common child! And what about the parents / siblings / extended family/ friends of Kidman? Would they also never visit for four whole years? If any one of them had, then they would have known the (fake) ex-husband had taken her out and would have called the real husband to get news. Then Kidman would have been reported as kidnapped.