From the website:
"Oblivion's Edge picks up right where Final Sanction leaves off, with the Battle-Brothers’ escaping from Lordsholm during the horror of the Tyranid invasion of Avalos. The Kill-team must strike back against the alien terror intent on stripping the world of all life, before it is too late.
As Oblivion's Edge is the direct sequel to Final Sanction, you may wish to use the pre-generated characters from Final Sanction, which can be downloaded from the Deathwatch Support Page.
Confront the most dangerous enemies of mankind and answer the call of the Deathwatch!"