Quantum of Nightmares - Book 2 of the New Management, a series set in the world of the Laundry Files

It's a brave new Britain under the New Management. The Prime Minister is an eldritch god of unimaginable power. Crime is plummeting as almost every offense is punishable by death. And everywhere you look, there are people with strange powers, some of which they can control, and some, not so much. Hyperorganised and formidable, Eve Starkey defeated her boss, the louche magical adept and billionaire Rupert de Montfort Bigge, in a supernatural duel to the death.
Now she's in charge of the Bigge Corporation, just in time to discover the lethal trap Rupert set for her long ago .