Boundary

Boundary is a historical fantasy series by Eric Flint, set in an alternate 1880s London where the boundaries between dimensions have shattered. The series blends steampunk technology with Lovecraftian horror, exploring the unsettling consequences of cosmic incursions and the desperate efforts of a secret society to contain them. It's known for its grim, realistic tone and detailed world-building, portraying a world grappling with existential threats alongside Victorian social issues.