Keith watches from the fish 'n chip shop window as his miserable, arguing parents leave, bickering as they drive away. Keith embarks on a mission to cheer up his parents, first deciding to paint the shop Tropical Mango to cheer, then buying a brilliantly coloured tropical fish.
Keith lies awake as his parents, Vin and Marge argue. Keith knows unless he does something drastic to improve their situation, his parents will split up. Keith must find out where the best fish comes from. The only one who will come near him on the bus is Ali as he has a cold and can't smell Keith's fish.