Hormones influence our lives. Just like our nervous system, they transmit information in our bodies. When our hormonal balance is disrupted, our behaviour changes and we may fall ill. But what are hormones? Why have they got such a big influence? Where are they produced? And how do they work? The film leads us inside the human body – into the world of hormones. We learn that there are various hormones, where these are produced and how they work. We get acquainted with people whose lives have been influenced by a hormone deficiency or a hormone excess.