Captain, Ladybird and Herbert – two Shire horses and a Suffolk Punch – are not pleased when Jenny, a retired seaside donkey, arrives at the Old Horses' Home. It's supposed to be a home for horses, and they don't want to share their field with a common little donkey. Then rustlers are spotted in the area: thieves who like nothing better than to steal horses and ship them abroad – to be made into horse pie! Can Jenny and her friends save the huge heavy horses?