This deal is from the Manchester Congress teams finals. After North has opened two notrump, South raises to four notrump quantitively and North gives up. Alternatively South may transfer to hearts and then bid four notrump. However, the main interest in this deal is that six hearts makes on a double dummy line.
If you were in six hearts undoubtedly you would try to guess which opponent held the ace doubleton of trumps and hope that the club finesse was working. This line of play would be unsuccessful.
However, by ruffing a couple of winners in the South hand and a club in the North hand and taking the club finesse you can reach the end position below with North on lead.
When the jack of spades is played if East trumps with the ten, South overtrumps and finesses the heart eight to make twelve.
This end position is known as the Devil's Coup.
It is probably not worth learning the mechanics of this type of end position, I know of no-one who has played a Devil's Coup at the table.