Status Updates From Black Sun (Alexander Vasin #1)

Every single last character in this book could be described either as "lost" or "holding on by their fingernails". The atmosphere continues to be very good, but the investigation is losing itself a bit in the descriptions of what a ruse these people's lives are.

1961 in a Russian city that exists on no map where they're building the world's biggest bomb. Great atmosphere and excellent historical vibes. Not as mystery-esque as Martin Cruz Smith nor as deep Soviet as Tom Rob Smith, but pretty good.