Twiga the giraffe is going to have a baby! An excited Koko has been given the job of keeping watch overnight, and fetching Dr. Gosling, the vet, if Twiga goes into labour. That night Mtambo (the safari tour guide train) tells Koko all about nocturnal animals. Koko learns how they use their senses to get round in the dark. When Twiga goes into labour, Koko goes to fetch the vet.