While the number of Bully's rats continues to grow, so does the number of missing animals. When Dash sees Plucky being taken away in a cage to a truck, she decides to follow the truck only to be shut out of a mysterious human establishment surrounded by high walls and spike-top gates. Meanwhile, the Weasels to stay at a farm but the animals wouldn't let them stay. They gain a new Protector who is Rollo the Sheep Dog.

The weasel family are still looking for another home away from White Deer Park. While the rest of the Farthing animals are still trying to find out where the missing animals are. It is up to Whistler to solve it. He follows the truck to a walled-in nature reserve. When Plucky finds him, he tells him that the place is a new sanctuary. Although it's a nice place, many of the animals were separated from their families. Meanwhile Owl is still trying to escape the moth-eaten Rook, who says he loves her, but gets into trouble when she hides in a house.

The two snakes find their way to Bully's nest after speaking to a rat with a feeling of impending doom. However Bully manages to escape leaving Adder and Sinuous frantically racing through tunnels with overwhelming numbers of rats looking for a way out. Adder reaches the surface but Sinuous turns the wrong way and ends up trapped underground. Toad tells Fox about the dwindling Frog numbers due to the rats eating them and Fox agrees to get the foxes to stand guard around the pond. Whistler informs Plucky about the events happening in White Deer Park and how they need his help to fight the rats. When the gates to the new reserve open to let out a van Plucky takes his chance to escape and jumps into the back of the van. However it goes the wrong way, but it is forced to stop when sheep block its path. Plucky jumps out and races back to White Deer Park. Meanwhile Owl is devastated when Hollow tells her about the pretty young owl he intends to become his mate once mature. Owl refuses

The animals in White Deer Park are still trying to deal with the army of rats and try to make the Warden aware of the problem. Meanwhile the weasels and the piglet come across a copse with a grumpy Wild Boar living there. Bully forms a task force to hunt down and kill the snakes. They find Sinuous, thinking it's Adder and kill him. Hurkel and Shadow try to comfort Adder as Bully slinks away unnoticed.

When the weasels return home, all the animals are overrun with joy. Fox explains their problem with the rats to the weasels and asks for their help. They agree, but first they must train Fido and Cleo on how to deal with rats ... using Spike as a volunteer. Mossy tells Hurkel that he found Shadow in a hutch by the Warden's cottage. While Hurkel and the weasels try to get her out, the Warden's cat summons Rollo to get rid of them. Of course, he recognizes his weasel friends and is very happy to see them. Meanwhile, after a few fights for leadership of the herd, the white deer and Farthing animals name Laird as the new leader of White Deer Park. Elsewhere, the rats, at their largest number yet, prepare to launch a massed attack on the animals of the park.