Thomas has a new friend in the Yard, Emily, and she is determined to prove that she is as Really Useful as Thomas. One day, she challenges Thomas to a race. Whoever can do their jobs the fastest is the winner. Soon they are off, each on a whirlwind rush around the Island of Sodor. But they both realize that speed is only part of being Really Useful...the work must be done right.
Rushing from stop to stop, Thomas and Emily each try to be the Most Really Useful Engine of all!