M. G. Leonard  

Danger at Dead Man's Pass (Adventures on Trains #4)

Kidnap on the California Comet (Adventures on Trains #2)

Murder on the Safari Star (Adventures on Trains #3)

Sabotage on the Solar Express (Adventures on Trains #5)

The Highland Falcon Thief (Adventures on Trains #1)

The Arctic Railway Assassin (Adventures on Trains #6)