Ben Fogle and Kate Humble explore life behind the scenes at Longleat Estate and Safari Park. White rhino bull Winston becomes a sperm donor. The Pere David deer are hovering on the edge of extinction, so can Longleat help save the species? The bat cave needs a makeover, but first Darren and his troops must round up the bats. Plus, a stake-out to see the lions tucking into a special midnight feast.