In her first major role since becoming a breakout star on Netflix’s Stranger Things, Millie Bobby Brown plays the title character in Enola Holmes. Anyone wondering whether Brown can do more than play Stranger Things’ Eleven will have their doubts silenced by her charming turn as the witty, headstrong younger sister of renowned detective Sherlock Holmes (Henry Cavill). Based on the first installment in Nancy Springer’s six-book YA series about Enola, the movie begins on Enola’s 16th birthday, when she wakes to find that her beloved mother Eudoria (Helena Bonham Carter) has disappeared. Enola’s father died when she was a small child, and her much older brothers, Sherlock and Mycroft (Sam Claflin), left home around the same time, so her mother has been her constant companion her entire life.

With the men of the family gone, Enola had an unconventional upbringing and was educated in literature, science and physical combat rather than the stereotypically ladylike pursuits of her era, like embroidery and music. When her older brothers return home following Eudoria’s disappearance, they’re appalled to see that Enola’s been reading up on feminism and doesn’t even wear a hat and gloves. Enola narrates all of this backstory directly to the camera in quick-moving sequences complete with onscreen text and illustrations, giving the movie a lively, self-aware tone from the start. Enola knows exactly how she flouts the values of her era, and she isn’t going to let her stuffy brothers hold her back.

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That’s not to say that they don’t try, though. While Sherlock is slightly impressed with his sister’s budding powers of deduction, Mycroft has no patience for her rebelliousness, and he determines that she’ll be sent to a snooty finishing school run by the prim Miss Harrison (Killing Eve’s Fiona Shaw). Enola feels that she has no choice but to run away, armed with the package of clues that her mother left her as a birthday present. She steals Sherlock’s old clothes so she can disguise herself as a boy, and she even says “The game is afoot” before getting on a train to London.

Enola’s quest to find her mother is quickly sidetracked, though, when she meets the handsome and somewhat hapless Viscount Tewkesbury, Marquess of Basilwether (Louis Partridge), a young lord who is also running away, trying to avoid the military service his family is foisting on him. He’s pursued by a mysterious man (Burn Gorman) who at first seems to be sent to retrieve him, but soon reveals a more violent intent. The movie somewhat awkwardly balances Enola’s investigation of Tewkesbury’s case (and their potential budding romance) with the investigation of her mother’s disappearance, and neither resolution is entirely satisfying.

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But the movie is still a lot of fun to watch along the way, thanks to Brown’s energetic and likable performance, which includes frequent cheeky asides to the audience (even soliciting viewers for ideas at one point) and clever commentary on her situation. Director Harry Bradbeer is a TV veteran who helmed nearly every episode of Phoebe Waller-Bridge’s Fleabag, and some of Enola’s brief, knowing glances to the audience look very much like the expressions that Waller-Bridge would use on that show. But Enola is entirely wholesome, far more interested in gathering clues and fighting bad guys than she is in attractive men, although she’s clearly drawn to the foppishly good-looking Tewkesbury.

Bradbeer stages some impressive and exciting action sequences, including a train chase as Enola and Tewkesbury attempt to escape the assassin, and a close-quarters fight between Enola and the assassin in which she holds her own against a dangerous foe. Although she’s trained in martial arts (one of her mother’s contacts runs a secret dojo for women above a tea shop), Enola is just as likely to use her wits, and that combination connects her most closely to the Sherlock Holmes played by Robert Downey Jr. in Guy Ritchie’s movies. As Sherlock, Cavill is clearly a supporting player, although he gets his own moments of ingenious deduction, and he makes it clear that he could take the lead as the character if given the chance.

But this is Enola’s movie all the way through, and Bradbeer and screenwriter Jack Thorne never take the focus away from her or make her seem secondary to her more famous brothers. The two-hour movie drags at times, especially during a stretch when Enola is actually stuck at Miss Harrison’s finishing school, but most of it is rousing, crowd-pleasing entertainment, the kind of thing that would have worked well on a big screen but is still ideal for a family movie night at home. With five more books in Springer’s series, there are plenty more Enola stories that could be told, and any return from Brown would be welcome.

Starring Millie Bobby Brown, Henry Cavill, Sam Claflin, Louis Partridge, Burn Gorman and Helena Bonham Carter, Enola Holmes premieres Sept. 23 on Netflix.

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