Zoologist Nigel Marven explores the wildlife of the Canadian Arctic. Nigel returns to Churchill where the Arctic foxes have had nine tiny cubs, and beluga whales have appeared in the river. The first polar bears of summer are also arriving and Nigel is delighted to encounter one swimming at sea. With the weather getting ever warmer, he is able to venture further north and visits Cambridge Bay, where he witnesses a breathtaking wolf attack on a herd of musk oxen.