Abandoned by her owner, after years of faithful service, in a deserted quarry, Lola the digger yearns for some companionship. One day, she is discovered by some children, but her pleasure in their company is short-lived when they flee in terror after a group of hunters warn of a dangerous wolf on the prowl.
Lola gives refuge to a succession of mountain and woodland creatures, including the wolf himself, plus a fox and her cubs; a wild boar and her piglets; a pair of robins and their nestlings; a lost faun and a lynx, but none is able to remain long enough to become her friend and so she resigns herself to loneliness.
The quarry and surrounding land are sold, and the new owner has a young son, David, who himself is friendless in his new environment. Not only is he lonely, like Lola, but also he has been passionate about mechanical diggers all his life. When he chances upon Lola, he is overjoyed. His father suggests that they clean her up and give her a coat of paint. The children from the village hear about it, and so come to lend a hand. The quarry becomes their playground, and the digger their favourite plaything. With so many new friends, David and Lola are no longer lonely.