participant in the Royal Road Writathon challenge

Sixty odd years ago. The Mahdiyya uprising in central Africa is in full swing. Khartoum has fallen. A British force chasing Mahdist rebels discovers a forgotten portal to another world.

Current day. Cities and towns dot the floating land masses of New Victoria, the world beyond that portal.

But a dark secret from Earth's past, long thought destroyed has infiltrated this new/old land. The Society of the Black Sun believe that this world is, in fact, Hyperborea, and their rightful domain. They mean to have it back.

This is the story of a farm boy who yearns to be more, and of his family. Boring, hidebound, straightlaced. Or, so he believes.

When the Black Sun attack his floating island home in an advanced, experimental airship, Darnan Palanna will discover, not only who they are, but who he is meant to be.

Raiders of the Black Sun is an alternate history tale... In a dieselpunk setting... Laced heavily with pulp.

While it's a portal story, it's not isekai. Everybody who goes there goes there on purpose. There's even a train.