Allah does not wrong people in any way rather it is people who wrong themselves. (Surah Yunus: 44)
Whatever their circumstances may be, there is one significant feature that a great many people have in common: The great majority lead unhappy lives. 
The goods and property they own, the jobs they perform, and their loved ones are not enough to make these people happy in any real sense.
The reason why they suffer from sorrow and feel unhappy even in the best of circumstances is because they live at a distance from Allah. Allah grants people happiness only through faith, and only in this way it is possible to take full pleasure in the beautiful things of life. So long as no sincere faith in accordance with the Qur'an exists, it is impossible to achieve true happiness by any means whatsoever.
This audiobook highlights this important truth and calls on people to live out true and sincere faith. It explains that people really create with their own efforts the systems that prevent them from being happy and enjoying life's blessings, and which plunge them into sorrow. It makes it clear that the only way to be protected against secret unhappiness is to believe in Allah with a sincere heart. It reminds the readers that so long as people do not achieve this sincerity towards Allah, they cannot experience real happiness by any means whatsoever—and that the secret sorrows of this world may well turn to eternal torment in the Hereafter.