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.
The Autobots continue to work for NEST, now no longer in secret. But after discovering a strange artifact during a mission in Chernobyl, it becomes apparent to Optimus Prime that the United States government has been less than forthright with them.