Peter (
Liam Neeson) discovers his wife Lisa (
Laura Linney) has been receiving e-mails and text messages from Ralph (
Antonio Banderas), a man he never knew existed. Peter's obsession with this unknown rival escalates and, against the advice of his daughter Abigail (
Romola Garai), a hurt and vengeful Peter flies to Milan to seek out the mysterious Ralph and the truth about his relationship with Lisa.