The story of a man. Maybe two. A father who leaves home taking nothing with him but the mailbox and a suitcase. He sits on a garden bench, on the street, waiting for a son's answer. Every day he sends him a letter and every day he hopes to get a letter back. Every day he combs his hair, puts a tie on, and shaves to be ready to receive that letter by the time the postman passes by.

The young and promising genetics researcher Thomas Nielsen will stop at nothing to become the first person to identify the elements in man that trigger aggression. To achieve faster results he performs illegal tests on the convicted mass murderer Iparrah. But when Thomas one day gets caught, he injects the unauthorized test agent itself. This turns out to have unexpected effects ...