A Room with a Clue by Dean Fiala

The local game club has won a weekend in a mansion and decides to roleplay a mystery based on Lizzie's favorite childhood board game. Peter is assigned Professor Plum, and like his character is often lost in thought. Wendy is type cast as Mrs. White, the temperamental cook. Max plays Col. Mustard, the hard-charging and hard to understand Australian military man. Everyone hopes timid Susan can build up the nerve to play Miss Scarlett. Penny is a kindred crusader to the temperance champion, Mrs. Peacock. Gavin easily dons the wealth and position of Reverend Green. But as the game becomes all too real, the group realizes that they might have more than one murder to solve.