Completion is the third volume in the Darwinian Extension Trilogy. Over twenty years have passed since the Martian colony was founded and the planet has a thin but breathable atmosphere. The population now exceeds fifty thousand and yet the relations with Earth are still fractious even though the species cohabiting on Mars are highly compatible. The efforts to develop an interstellar propulsion system seem to stagnate when a breakthrough discovery is made. Tension on Earth reaches acute levels as a result, and this instability is compounded by approaching threat of internal nuclear proliferation by a renegade nation. This shakes the confidence of the alien species in humanity and its destructive potential.The contemplation of the Martian population toward physiological modification, in preparation for interstellar flight, exacerbates the situation and the 'alliance' hangs by a thread. Social viruses begin filtering into Martian society from new colonists arriving. Time is running out.