Max and Me and the Time Machine

Max and Me and the Time Machine by Greer, Gery. paperback edition. ISBN: 9780064402224.

When Steve brings home a time machine he bought for $2.50 at a garage sale, Max is suspicious. "There s no such thing as time travel. Or time machines." Then they both end up in the year 1250 in medieval England -- Steve as Sir Robert Marshall and Max as his horse! -- and Max must admit the machine works. Sir Robert soon finds himself in the midst of a duel to the death with the Hampshire mauler, defending not only his honor, but his life. Can Max rescue him? Will the machine return him in time to spare his life? The 20th century never looked so good.