Soo, the beginning of my favourite Stross series. You know: magic is advanced maths, kinda powerful geeks and really powerful burocracy.
I think it’s noticable that Atrocity Archives is an early Stross book. In the first half, the Shibboleth/Shibboleet dropping is sometimes very obvious and a bit annoying. (Redeeming Stross though, he is actually knowledgable enough to actually use all those jokes, tropes and catchphrases, so it’s ok.)
Plot: We meet Bob, who wants to join Active Service in the Laundry. Angleton and Andy, his bosses, send him to the USA, where he meets and saves Mo, who then returns to London and moves in with him (after Bob saves her again at her own doorstep).
To draw out their enemies Mo, Bob and secret reinforcements travel to Amsterdam for research, where Mo is promptly abducted to another universe. Bob joins the reconnaissance team. Turns out, in a close parallel universe to our own one, the Nazis finished their arcane project by summoning an Infovore and travelling to that world (some ice giants included). The Infovore sucked the universe dry and is now trying to get all of itself over to Bob’s universe. With judicious use of some Hands of Glory and an H-Bomb they manage to save Mo, Bob and about half the crew.