Elizabeth Masterson (Witherspoon) is a work-obsessed San Francisco doctor who is involved in a huge car crash after a mammoth, and probably illegal, 26-hr hospital shift and left in a coma. Meanwhile, David (Mark Ruffalo) is new to The Bay and moves into her apartment - but soon finds he is not alone, and is being haunted by her spirit. Worse, it seems that he is the only person that can see her, and the only way to get the uninvited guest out his apartment is to find out what she wants.

David and his little friend disguise themselves as doctors and try to kidnap the comatose body, but are stopped by the rival doctor who wants her dead. David knocks him out and, guided by Liz's spirit, they make a run for it pushing the body on its hospital bed chased by security.
  During a tussle, the breathing apparatus comes loose and David is surrounded. Liz is vanishing as the body is slowly dying.
  David leans over to give her the kiss of life, before he is wrestled and taken away by the guards - while the completely horrified sister (quite understandably!!) looks on, confused.
  Suddenly a heart beat is registered and Liz wakes up - but doesn't recognise poor David, who just walks away.

Times go by. She returns to the apartment, poor little David has been evicted it seems, but she knows something is wrong.
  She climbs up to the roof - and finds it has been turned into a beautiful garden oasis, with David there adding some final touches.
  He gives her the spare key, and as they touch all the memories come flooding back to Liz. They kiss and are both very much in love.
  Jon Heder, the best thing about this movie, is watching the whole scene in a snowglobe, and ends it all with -- "Righteous!!"