Final Onslaught - J J Green - Bog

Trapped on a dying planet
General Cherry Lindstrom made a decision that killed millions of a friendly alien species and threatens the future of humanity.
A deadly poison is creeping across the surface of her planet, but the allies of humanity won’t reach Concordia in time to mount a rescue.
While the scientists battle to find a way to neutralize the lethal toxin, Cherry is chasing down another threat: an enigmatic visitor who arrived just prior to the chemical attack.
Her guts tell her the new arrival is up to no good, but others think she’s wrong. For Cherry, finding and eliminating her target may be her only path to redemption for her fateful decision.
All hope appears lost for the Concordia Colony, but the final onslaught is yet to come.
Final Onslaught is book three in the second part of the space colonization epic adventure, Space Colony One.