Anyone who saw her dazzling turn in The Drowsy Chaperone last summer will already suspect it, but her performance as Maria Rainer in this classic Rodgers and Hammerstein musical confection eliminates doubt: Summer Strallen is a star.

She inherits the role from the reality-TV winner Connie Fisher, and her own route to the Von Trapp family manse has been similarly unconventional. Last October, Strallen joined Channel 4's soap Hollyoaks, playing a musical-theatre wannabe, Summer Shaw. Unbeknown to most of the cast and even to Strallen's family, plotlines were engineered so that television audiences could watch the character's pursuit of her dream as she hunted down Andrew Lloyd Webber and convinced him to cast her as his leading lady. Stage and screen coalesced on February 26, with Hollyoaks showing Summer Shaw making her stage debut, and Strallen's first preview at the Palladium half an hour later.

At 23, Strallen, the niece of Bonnie Langford, already has an impressive CV; she began her career at the age of 6, coincidentally with another production of The Sound of Music, in which she played Marta Von Trapp. But it's this performance that will make her name. True, there are few opportunities here for Strallen to display her terrific dancing talent, and in the early abbey scene her acting is slightly overemphatic; but she grows increasingly assured and her voice, smooth, warm and rich as liquid chocolate, is stunning.

The tall, leggy actress also brings a ripeness and a robust energy to the part that makes this Maria a persuasive country girl. Disarmingly cheeky with a winning seat-of-her-pants charm, she's likeably out of her depth in the palatial Von Trapp home, fondling the furnishings and stealthily cramming her mouth with pastry from a silver salver. But she blazes when she rounds on the authoritarian Captain, and, with her own childlike glee in rough-and-tumble games or mid-thunderstorm pillow fights, she conveys a bond with the seven-strong Von Trapp brood that is genuinely touching.

Jeremy Sams's production remains a delicious Viennese whirl of a show, elegant and sweet while stopping just short of toothache. And the cast is uniformly strong, with Simon Burke an imposing Von Trapp, Amy Lennox pretty, petulant and vulnerable as Liesl and Margaret Preece as a fine-voiced Mother Abbess. But this is Strallen's moment, and so successfully does she seize it that now there will be no stopping her.

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