Arriving at work one morning, Helen (Gwyneth Paltrow) discovers that she had been unjustifiably fired from her PR job. She is returning home when an amazing thing happens, time reverses itself for a few seconds and a second version of herself is created. In one reality Helen catches the tube, meets James (John Hannah) and arrives home to find her loathsome lover Gerry (John Lynch) cheating on her with his ex-girlfriend Lydia (Jeanne Tripplehorn). In the other reality Helen misses the tube train, gets mugged, goes to hospital and eventually arrives home to find Gerry alone in the shower. The two realities move forward in tandem; in one Helen leaves Gerry and forms a happy, new, loving relationship with James; in the other Helen's live becomes more and more wretched as she takes on two jobs to support her worthless, cheating boyfriend as he supposedly writes his novel but in fact carries on a torrid affair with Lydia.

We all have but one life to live. Helen gets two... at the same time