To discover which opening lead is best from a given West hand against a particular auction, the authors use computer software to generate 5000 deals that match the North-South bidding. (The West hand remains the same and the other three hands are chosen randomly. ) The software then plays these deals automatically, seeing which of the 13 possible opening leads works best at both IMPs (rubber bridge/Chicago) and match-point pairs. By analysing the results, the authors pass on to the reader the secrets of finding the best lead against notrump contracts on a wide range of different auctions.