As in Pratt's delightful Doors of Sleep series, this book features a cheerful, kind protagonist who finds himself hopping across worlds. Glenn's getting his PhD at UC Santa Cruz when he learns his girlfriend (& domme) Vivy is actually a freedom fighter for the Interventionists, a group dedicated to stopping the spread of fascism between worlds. It is in no way explicit, but it's funny how the kink is a more surprising plot point than, say, aliens.