I don't normally read horror or spy fiction and this is both but came to me highly recommended. It isnt quite a 1st novel, more like two long novellas in the same universe.
And I do pass on the recommendations.
I enjoyed the stories but god I never ever want to visit, let alone live in, that universe.
Quantum mechanics, alternate universes wherein dwell the great old ones, (unpublished) number theories by Turing that unlock the laws of physics*, necromancy on a computerised, industrial scale (think Auschwitz as an attempted answer to the Manhattan Project). Oh and a British secret agency* that ensures loyalty via a very nasty geas...
* Into which the main character was drafted after he accidentally rediscovered said theories and before he could accidentally rearrange a largeish (city sized) chunk of the British landscape...
If you cannot see the causal relationship between "I have chocolate" and "Life is Good", you simply aren't trying hard enough. Pirates of the Burley Griffin