Deathwatch

Deathwatch by Steve Parker. paperback edition. ISBN: 9781849704465.

When they first came together, Talon Squad were a disparate group of Space Marines from various Chapters. Under the auspice of the Deathwatch, trained in an ironclad Watch Fortress, they become a kill-team. Alien hunters, experts in xenos extermination, their first mission under the mysterious Inquisitor Sigma is a deadly one. Of all the enemies the Deathwatch face, the genestealers are amongst the fiercest, the most invidious. Led by Brother-Librarian Karras, Talon Squad must penetrate the bowels of a genestealer lair and put the abominations to the flame or face the consequences of an entire planets extinction.