Critical Series by Darren Wearmouth, Colin F. Barnes

Some mysteries should stay buried. 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. A centuries old plan unfolds... moreSome mysteries should stay buried. 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. A centuries old plan unfolds. Pippa, Charlie, and the rest of humanity will have to fight for survival, sacrificing the life they've known to protect Earth from an ancient and previously dormant enemy. Even that might not be enough as this new enemy exacts a plan that will change the course of humankind forever. Critical Dawn is an apocalyptic ride to the very edge of human existence. Factions will battle for control of the Earth-if they can avoid the threat of extinction. less

Fighting back and destroying alien ships has grave consequences. Earth faces its ultimate destruction, unless bitter enemies can work together. Earth is recovering after Charlie 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... moreFighting back and destroying alien ships has grave consequences. Earth faces its ultimate destruction, unless bitter enemies can work together. Earth is recovering after Charlie 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. The team encounter a hybrid city, where humans and croatoans live and work together. It's here in this strange new civilisation that Denver discovers there's a bigger threat to the planet than the aliens already on the surface: something far more terrible is coming, and it's a race against the clock to save every survivor from the impending onslaught. Critical Path is the republished exciting sequel to Critical Dawn. less

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 which 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 find a way back to Earth-if there is one. An old enemy of Unity is intent of making them pay for his humiliating treatment. He's gathering forces to the south with vengeance in mind... moreA 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 which 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 find a way back to Earth-if there is one. An old enemy of Unity is intent of making them pay for his humiliating treatment. He's gathering forces to the south with vengeance in mind. Mike and Mae must work together with the citizens of Unity to find a way of repelling Augustus' force, or face extinction at the hands of the old emperor. Critical Strike is the republished exciting third instalment of the Invasion Trilogy. less