The Signal (PLANET NINE TRILOGY) by SEBASTIEN ACACIA

2020, Astrophysicist Anthony Hallbrown is desperate to decipher a signal coming from space with the help of Yoko, a Japanese expert in cryptography. They will discover that the source of the signal is none other than the ninth planet in our solar system, never yet officially observed. But their discovery will awaken the Partisans, a former sect led by Asarus Hicks who claims to be the legitimate servant of space travelers, who, according to the theory of ancient astronauts, had come to Earth to genetically create the human race hundreds of thousands of years before our age.