We get to know some of the incredible animal heroes at the park who are helping their wild cousins across the world. One such animal is Anne the Asian elephant, who was rescued from the circus and rehabilitated, thanks to the tireless work of her keepers. When she arrived at the park in 2011, Anne was in such poor physical condition that she couldn't even lift her trunk, but over time, the oldest elephant in Europe is now in good health. One of her biggest issues is typical of old age in both humans and animals — arthritis. Anne has been treated for this by specialist animal osteopath Tony Nevin. His pioneering work on Anne has been so transformative and successful that Tony is now taking the knowledge he has gained to the other side of the world to rehabilitate captive elephants in Thailand. We join him and the keepers on their epic journey. Hamza Yassin is set a "spot the difference" challenge, but with a wild pair of wildebeest. It's vital that the keepers are able to identify their animals quickly, if there is a medical issue for example, so they always collect a list of differences to know their animals better. This is often a simple process, but with wildebeest brothers SJ and Ky, it's quite a challenge because they look almost identical. Thankfully, Hamza is on hand with his zoom lens camera to analyse the brothers in extraordinary detail. With them constantly moving and swapping over, this is no easy task. Can Hamza deliver three distinct differences to the keepers? In an episode where we are celebrating animal heroes, Kate couldn't resist meeting Monty, the first male southern koala to be born in Europe.