A magical creature lost far from home leads the four O'Hero-Smith children on another adventure through the Which Ways and across the galaxies; their plan is to get 'Grub' back to the ice-encrusted planet where he belongs, and to prove to their parents that they can be trusted with magic along the way! But by setting off on this secret mission, they're heading straight into danger. Not to mention they've accidentally left Annipeck on her own. Again. Can the kids get Grub home safely, escape venomous snow sharks, a witch's curse and an army of murderous robots to find their way back through the Which Ways to protect her?