When the Aldens spend the summer riding on a train, they get to live in a train car once again - this time, they're staying in Caboose No. 777. The number is hard to forget, and indeed, the children meet people at each stop who seem to know it well. It turns out Caboose No. 777 has an unusual past - one that comes with its very own mystery!

The adventures of the four Alden children as they investigate a mystery that took place in the yellow house on Surprise Island many years before.

"Eva Wingdale and her class are excited about their trip to Poppy's Pumpkin Farm, where every year, there is one very large, extra special, thank-you pumpkin; but on the second day of the visit the owls find that the Thank-you Pumpkin has gone missing, and the farm animals are in an uproar -- so Eva and the other owls turn detective to solve the mystery of the missing pumpkin." --