Rainy days are digger days. Plitschplatscheratschditschvitteldatsch, the rain drums against Robert's bedroom window. And it's been doing this for days! Just as grumpy and gray as the sky is Robert's mood at the moment. What miserable, cold weather! Especially now that his first summer vacation has finally started. Good thing Robert has his big yellow digger! Before the city he just built in his sandbox sinks in the rain, he tries to use the digger to pluck the rain clouds from the sky. But just as Robert takes a deep breath, it pours worse than before! So he sets off with his digger in the direction from which the clouds are coming. On their journey, they traverse various countries and landscapes of this earth. Finally, they reach Nepal and uncover the cause of the never-ending rain in the Himalayas.