After "The Cake", Alexandersson and De Geer just barely got away with another contract for television, although this time they had to promise that it would be a series for small children.

Karl Krall was a person that had lived in Germany at the beginning of the century, and was to become the mold for the veterinarian-character played by Krister Broberg. Brehm's "Animal Life" was also a source of inspiration. Doctor Krall is the kind of guy that doesn't trust other humans, he only trusts animals. He combats the diseases and depressions that affect rats, frogs, rabbits and horses, as well as standing up to his assistant Rolf's all too great enthusiasm. Krall treats Rolf as a wretched, old-fashioned schoolteacher might treat his students. The world that these two live in has entirely its own form of bisarre logic. The two desert rats, Hans and Greta also play important roles in this chamber-drama. Often are the times when Doctor Krall comforts himself by playing tunes on his beautiful, walnut Hammond organ.

The Doctor, with his painful and sometimes bombastic outbursts (and organ playing) is a figure not entirely unlike Albert Schweitzer. The assistant, Rolf, in his faded graduation cap and all, is a down to earth, but unlucky sort of realist that tries to understand the master's visions, although somewhat in vain. Krall became a myth for the youth of the 1970s, and every once in awhile one could see grafitti on the subway walls: "Doctor Krall lives!"