Principio, Meio e Fim is not an easy one to explain.
But it is definitely special because it tries, very valiantly, to allow writers and creators to share the same level of limelight the actors do on every show.
So here's my best attempt to explain what the show is about, relying also on a free translation from the Portuguese synopsis:
Every week, 5 friends meet up for dinner. What they don't however, is that they are fictional characters and the events of the dinner will be shaped by creativity (or lack therefore) of 4 (comedy) writers.
So we see, on a weekly basis, how writers come up with entertaining scenarios which are (to a degree) confined to a living room and 5 lightly described characters.
The rules are simple - they have 2 hours to write whatever they want, and not a single second more. When the time comes, whatever typo, continuation error or plot hole left must be acted out as is written on the script.
This makes up for a naturally bipolar episode composed of two parts
1) the 4 writers' creative process, as they struggle with the deadline and the coherence of their ideas; and
2) the actors acting out whatever was written in those two hours (which are condensed into c.10mins for the episode) - including every mistake that made it to the page
Both the creative process of writing AND the actors loyalty to what is clearly a far from ideal script (with unnecessary screams, for example) make for a very entertaining watch.
Bruno Nogueira (Último a Sair, Sara) has done a successful show yet again - and this time in particularly innovative fashion.