Short filler volume
Not really much happened in this volume. Couple new faces, potential intrigue at best. They don't even wrap up the last volume's cliffhanger endings in a satisfactory way, just handwaved. You could almost skip this volume and go straight to #4.
Oh, unless you are here for the multiple page fan service of Garnet in the bath... Which I could have done without. Made for weird visuals matching with the dark backstory dump.