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.