What to read after Justice Keepers Saga - Books 4-6?

Books 4-6 in R.S. Penney's 'Justice Keepers Saga', a series of science fiction novels, now in one volume!

Relativity: Anna and Jack are on a mission to recover a piece of technology from the mysterious Overseers, the aliens who scattered humans on planets throughout the galaxy. With the device's strange effects on the human mind, Anna races to Tennessee to retrieve it, while Jack travels to Leyria to make contact with a professor who studied the Overseers. As they uncover the secrets of the Overseers, a vengeful Wesley Pennfield returns to Earth, complicating their mission and endangering their lives.

Evolution: A campaign of terror is underway on Earth as Justice Keeper Grecken Slade seeks to control the mysterious Overseer technology known as the Key. Jena Morane leads a resistance against Slade, while Jack Hunter and Harry Carlson search for the ciphers that will unlock the Key's secrets. But something ominous is lurking on the edges of space as the Overseers return after ten thousand years, signaling a shift in the galaxy's fate.

Dirty Mirror: In the aftermath of their worst defeat, the Justice Keepers retreat as a new threat arises. Melissa Carlson, a Justice Keeper trainee, finds herself caught up in a terrorist group's plans to upend the peace of Leyria. Meanwhile, her father Harry struggles to adapt to the changing world around him. In this exciting new installment of the Justice Keepers Saga, Jack Hunter launches an investigation to uncover traitors among their ranks, shaking up everything readers thought they knew about this epic space opera.