How do I play a three or four player game?  There aren't enough Character cards.

 

The set comes with two sets of Character cards.  To play three player a set of proxy cards must be used (downloadable HERE). 

 

Then play proceeds as normal, in a clockwise fashion.  Each player has a set of Pillars, investgates separately and has their own Case Log  and hand.

 

UPDATE: There is a third set of Pillars included in "A Night at the Lizzie Borden House" and "A Night at the Grand Midway Hotel" expansions, each with a new Psychic character.

 

To play a four player game, you play in teams.  Each team shares one Case Log  and acts as one player, but each person has a hand of six cards and takes a separate turn.  Play goes clockwise, so "Team A" would take two turns (one per player) and then "Team B" takes two turns.  Any game text that targets a player still only affects one player - the holder of the card chooses if not specified by the card.