Warriors In Winter (Magic Tree House) Mary Pope Osborne

Travel back in time in the magic tree house with Jack and Annie in this #1 bestselling series and meet the greatest warriors of all--the Romans! We are warriors! Jack and Annie have met knights, pirates, ninjas, and Vikings, but they have never met the most fearsome warriors of all: Roman soldiers. When the magic tree house whisks them back to the early 100s AD, Jack and Annie find themselves in a Roman camp. Their mission: Be like a warrior. That is easier said than done! The Roman soldiers are much scarier in person--and suspicious of strangers. Then a mysterious man riding a black horse gives Jack and Annie some advice to help them on their mission. But the man may not be who he seems. Will Jack and Annie be good warriors? Can they learn what makes the Roman soldiers so great? And who is the mysterious rider . . . ? Did you know that there's a Magic Tree House book for every kid?
Magic Tree House: Perfect for readers who are just beginning chapter books
Merlin Missions: More challenging adventures for the experienced reader
Fact Trackers: Nonfiction companions to your favorite Magic Tree House adventures If you're looking for Merlin Mission #31: Summer of the Sea Serpent, it was renumbered as part of the rebrand in 2017 as Merlin Mission #3.