Trilogy of Dhana and the Earth. Book three. Invisible enemy

Two thousand years have passed since the so-called «The end of the World» described in my first book. A thousand years ago, reptilians were defeated. Awakening of the planets’ consciousness helped people, after all, the planets have even changed their names. Terra, Dilly, and Masha created the «Union of Three Planets» for protection from external threats. A millennium of peaceful life has come. Why does sadness dominate the planet? The heroes of my new novel will have to deal with it.