The first episode sets the scene and introduces us to the main characters and starts to show us what it is like to be only 15cm high. We find out that they are the only borrowers in the house and also meet the humans that co-inhabit the house. The first of a series of problems start with Pod 'being seen'. Arrietty, who has never been allowed out of their below the floorboards home, is introduced to the art of borrowing.

While on a trip out Arrietty is seen. Thankfully this is by a young boy that is living in the house and he does not have the usual adult reaction to the borrowers. Unfortunately, his naivety later leads to problems but initially Arrietty asks him to deliver a letter to a place she hopes might hold another family of borrowers.

Things look too good to be true with their new human friend bringing them more presents than they know what to do with. Unfortunately, it is too good and the family of borrowers is discovered and the rat catcher is called in.

The first two thirds of this episode are a wonderfully crafted and tense escape sequence with the rat catcher on the job and poisonous gas being pumped into the wall cavities. The last third sees our family out in the big wide world, and when you are only 15cm high the world is very big indeed.

The family have taken up refuge in an old boot that they have found in the forest. This is the base camp for Pod's excursions out to try and find another family of borrowers, one that is supposed to live in a badger's nest somewhere nearby. This episode introduces a new borrower, a young boy about Arrietty's age that lives in the forest.

Things take a turn for the worse as the boot that the family is sleeping in is picked up by the rat catcher and taken back to his caravan. The young borrower from the forest and the young boy from the house have to join forces to attempt a rescue.