Here's a brief guide to help you understand what "Vigilus Alone" is about:

The novel takes place after the events of the previous Gaunt's Ghosts novel, "Uplink Alpha". The story follows Captain Ciaphas Cain, Commissar of the Valhallan 12th Regiment, and his aide and lover, Amberley Vail, as they navigate the underworld of the planet Vigilus.

A niche topic!

"Vigilus Alone" is a popular Warhammer 40,000 novel written by Dan Abnett, published in 2008. The book is part of the Gaunt's Ghosts series, which is a series of novels and short stories set in the Warhammer 40,000 universe.