Matt and Anna are a young couple living in London. Anna is starting her career and knows what she wants, whilst Matt is still struggling to find his purpose in life. On the surface they are happy but tensions are beginning to mount.
Then one morning masked thugs break into the flat and kidnap Anna before assaulting Matt, locking him into a mysterious vest and leaving him a mobile phone. Matt is told the vest contains a package which he must deliver by following instructions issued to him via the mobile phone.
If he fails, tries to seek help, or deviates from their instructions, they will kill Anna. Over the course of one day Matt has to make his way across London in a desperate bid to save his girlfriend as a host of characters attempt to derail him from his mission.