Dark Forces./ Stephen Leather.

A violent South London gang will be destroyed if Dan
'Spider' Shepherd can gather enough evidence against them
while posing as a ruthless hit man. What he doesn't know
is that his work as an undercover agent for MI5 is about
to intersect with the biggest terrorist operation ever
carried out on British soil. Only weeks before, Shepherd
witnessed a highly skilled IS sniper escape from a
targeted missile strike in Syria. But never in his wildest
dreams did he expect to next come across the shooter in a
grimy East London flat. Spider's going to have to proceed
with extreme caution if he is to prevent the deaths of
hundreds of people, but at the same time, when the crucial
moment comes he will have to act decisively. The clock is
ticking, and only he stands between us and Armageddon....