Priests of Mars by Graham Mcneill

[dragon]

Didn't see it posted anywhere but it was a decent read with a lot of twists and turns in the plot. Of course just about everything was thrown into the mix with the Ark Mechanicus full of Magos in conflict with each other, Space Marines, Cadians, Titans all on a grand expedition fighting all sorts of fun things like Eldar warships and Ork Servitors. Oh in addition the 3 pressed crew members. Plus the hidden secrets that await to be discovered on their ships. Like the Spoiler

Machine Spirit of the Ark being sentient and the hidden Black hole cannon no knows about as well as the Chrono weapons but then it was built during the golden age.