The reading of the will indicates that the heirs will be paired with another person and that each pairing will be given a set of clues which they are to keep secret from the others. They are to use the clues to figure out who killed Sam Westing. It's a great big "whodoneit" mystery, but the thing the heirs don't realize is that Sam isn't dead. Only the young girl who kicks everyone (Turtle Wexler) figures out the use of Sam's aliases which all have to do with the directions (Julian R. Eastman, Barney Northrup, and Sandy McSouthers). Anyway, the pairing who figures it out will win the contest. Each pair is given 10,000 to use as they see fit while they play the game.
The partnerships are decided in order to provide the "help" each member needs...love, acceptance, guidance, consolation, companionship...whatever that may be. As they seek the Westing fortune, each pair becomes a partnership, friendship, and eventually part of the community. So, everyone gains something...even those who don't win the game.