Tom, greeting-card writer and hopeless romantic, is caught completely off-guard when his girlfriend, Summer, suddenly dumps him. He reflects on their 500 days together to try to figure out where their love affair went sour, and in doing so, Tom rediscovers his true passions in life. After being dumped by the girl he believes to be his soulmate, hopeless romantic Tom Hansen reflects on their relationship to try and figure out where things went wrong and how he can win her back.