East Africa. It's the time of the great wildebeest migration. Hundreds of thousands of them are gathered on the grasslands of the Serengeti Plain, waiting to set off on the next stage of their epic trek. For one impatient wildebeest, he spends the time rushing about telling everyone how wonderful he is; the biggest, bravest wildebeest ever; with the strongest, curliest curly horns; the thickest, bushiest bushy beard; the longest, swishiest swishy tail, which is how he got his name: Mr Wildeboast. Eventually, they set off. It's a long journey, takes many months and is fraught with many dangers, like hungry lions and crocodiles. In September, they reach the banks of the Mara River, where, after all his posturing, Mr Wildeboast is faced with a sudden and terrible truth. He can't swim! But, to survive, he has to cross the river...