"World's Greatest Sleuth!: A Holmes on the Range Mystery" by Steve Hockensmith
The fifth mystery featuring Gustav ("Old Red") and Otto ("Big Red") Amlingmeyer. Here, Hockensmith takes his cowboy detectives to the 1893 Columbina Exposition in Chicago to take part in a mystery contest to determine the world's greatest detective, to find out what famous crime solver will take the mantle from Sherlock Holmes (Holmes is a real person in these books, though he's recently met his end at Reichenbach falls)
The contest appears to be mainly one of solving puzzles, in order to find a hidden golden egg. The puzzles are written by Armstrong Curtis, a Holmes follower who is eager to show that the other detectives are frauds. Judging the contest is William Pinkerton, who doesn't compete since he thinks the contest is below him.
The first round is won by French detective Eugen Valmont, and with the second one, Armstrong Curtis is found dead (in a large mound of cheddar cheese). The Amlingmeyer boys quickly decide Curtis was murdered, though they get no support from their fellow detectives.
The Chicago World's Fair is a great setting, as it allows the Amlingmeyers to gawk a bit at the wonders (juciy fruit gum!). There's competition between publishers, and the other detectives provide a nice counterbalance to our cowboys (there's a great scene with the Frenchman Valmont facing off the various suspects). As with the previous books, there's also a hint of romance, as one of the detectives taking part is the lovely, tough Diana, who both the Amlingmeyers are sweet on. And who is the mystery man who congradulates Otto on his detective skills near the end of the book?
Hockensmith has done a good job with the series, since each plot is different, with this one being almost a screwball comedy (a nice change of pace after the serial killer plot of "The Crack in the Lens"). It'll be nice to see if he can keep up the quality.