It's not just that she doesn't forget anything - she physically can't forget anything. Pick any day of her life and she can recall in exact detail what she saw or heard: faces, conversations, clues... all of which comes in very handy when you're a detective.
The murder of her sister when she was eight years old inspired Carrie to be a cop and, working as a detective in Syracuse, New York, she had an unprecedented 100% case closure rate thanks to her flawless memory. But, when her sister's murder investigation was eventually shut down, Carrie put her past behind her, quit her job and moved to New York City to start a new life.
That's when her former boyfriend and partner, Lieutenant Al Burns (Dylan Walsh), stepped into Carrie's life once more, asking for help with solving a case. Although initially reluctant to get involved in police work again, Carrie joins the New York City Police Department's Queens homicide unit and soon realises that working with Al and his team, including medical examiner Dr Joanne Webster (Jane Curtin), could be a move in the right direction.
And it might even help uncover the one thing she has been unable to remember - what exactly happened the day her sister was murdered and who killed her.