Beyond the Pale (1997)

From back of the book:

The Venusian Apocalypse

Venus: the jewel in the crown of Bauhaus, site of their greatest cities and most productive factories. Home to two Cathedrals, and millions of staunch Brotherhood supporters. Venus is a bastion for the Brotherhood on the face of the evil of the Dark Legion. Yet might Venus stands as one of the largest and least explored of the colonized planets and hidden within its deep jungles are secrets that could undo all mankind. When the greatest of all evils escapes its bonds to wreak havoc there can be only one result: the final destruction of Venus and maybe the whole system. Unless of course someone can stop it first.

Beyond the Pale

Here, in the exciting conclusion to The Venusian Apocalypse, the streets of Heimburg erupt into all out war with Dark Legion and Brotherhood troops fighting for every block of every neighbourhood. In the midst of battle, another more deadly plot is developing. Its purpose: the destruction of the Cathedral and of life as we know it on Venus. There is only one night left before all is lost. Only a few hours to find out who is behind the war in Hemburg's streets and save the city, the planet, and possibly humanity...