Watch The Stranger Within Full Movie Free Online 123Movies. After a traumatic ordeal, acclaimed actress Emily Moore and her psychiatrist husband, Robert, escape on a relaxing vacation to a gorgeous remote Mediterranean island. But on the first night at the house, a young girl arrives, blood on her hands and hysterical from the death of her boyfriend in a hiking accident. Robert offers to take in and help the young girl, but her suggestive behavior makes Emily wonder if she might be a threat to their marriage... or her life.