The roster of young actors who’ve played Dorothy in “The Wizard of Oz” at the Children’s Theatre consists of Maeve Moynihan, Britta Ollmann and Broadway star Laura Osnes. Add Traci Allen Shannon to that illustrious gallery. On Friday, Shannon opened in the lead role in director Peter Brosius’ massive, and massively entertaining, revival of “Oz.”

Shannon is a more developed artist than her predecessors and that maturity is evident from the top of the show. She begins “Somewhere Over the Rainbow” quietly, telegraphing Dorothy’s uncertainty about her desire to escape with Toto. But as things become clearer in Dorothy’s mind, and as her doubts leave her, her voice firms up and she begins to soar, taking us along with her — not just over the rainbow, but over the moon.

That Shannon imbues her delivery with evident thinking and a story arc adds layers of meaning to her sweet singing. Her smart, emotion-tugging acting also shows similar depth and dimension, which helps to make Brosius’ production a winner. Scott Bradley designed the vibrant set while Helen Huang dressed the characters and Paul Hackenmueller lit it all.

“Oz” has always been a show of moral lessons and life metaphors. Dorothy, an unsettled teenager on the Kansas plains, dreams of life in a better place. After being caught in a tornado, she finds herself, with Toto, amid strange creatures in a land called Oz.

Getting home requires her to get in to see the Wizard (the venerable and pitch-perfect Gerald Drake) and to fend off the Wicked Witch (Mary Fox). She does so with a Tin Man (Bradley Greenwald) who wants a heart, a Scarecrow (Dean Holt) who wants a brain and a Cowardly Lion (Reed Sigmund).

The CTC revival, which runs for a taut two hours, including intermission, is like a luxury steam engine barreling down the tracks with conductor Andrew Cooke’s swift baton and Joe Chvala’s mirthful choreography.

While Shannon’s Dorothy and the cute, nearly ever-present Toto (Dusty and Nessa alternate in the role) are the stars, “Oz” gets comic juice from the likes of Sigmund, who puts on the tail and the whiskers of the Cowardly Lion for the fourth time. With his witty, expressive face and funny vocal stylings, Sigmund compares favorably to Bert Lahr, who played the part in the 1939 film on which this Royal Shakespeare Company adaptation is based.

Holt’s Scarecrow also is a glob of seemingly gelatinous fun. The actor, who also is a decent singer, excels at knockabout physical comedy, and from lunge to pratfall, he does not disappoint. Greenwald gives his robotic Tin Man a lot of heart.

Fox gets a lot of mileage out of the Wicked Witch’s external signs of difference — her long nose, her broomstick with a torch embedded in the end and green face paint. But her real power comes from within; her cackling alone scared the children around me on opening night. The Children’s Theatre has got it down to an art, and a science.