The Critical Series

Archaeologists Pippa Quinn and Charlie Jackson find advanced technology in undisturbed 16th-century graves. A portent, the discovery precedes thousands of giant sinkholes opening up across the globe as extreme weather threatens the population. Charlie suspects the two are related.

Destroying the croatoan's seat of power has grave consequences. Earth faces destruction unless bitter enemies can work together. Earth is recovering after Denver and his group managed to stamp out the immediate alien threat. Now Denver and his team, stationed in a liberated croatoan farm, plan to restore humanity as the dominant force. But when shocking information comes to light, they set off on an immediate mission north.

A fight for survival in an alien world. Revenge is planned against Unity. Denver, Charlie, and Layla are trapped in the middle of a galactic conflict that has spanned across many millennia. With no immediate allies on either side, they must use all of their skill and strength to stay alive and to find a way back to Earth - if there is one. An old enemy of Unity is intent on making them pay for his humiliating treatment. He's gathering forces to the south with vengeance in mind.