“I write this sitting in the kitchen sink,” begins young Cassandra Mortmain in Dodie Smith’s much-beloved novel I Capture the Castle. Composer Steven Edis and librettist Teresa Howard, in their adaptation of that book now playing at the Watford Palace Theatre, have thrown in everything but.

Despite the nifty set, talented cast, and the sturdy backbone of Smith’s young adult classic, this tonally disparate new musical retains all of the book’s familiar love story but little of its witty, wise storytelling magic. What makes the novel so memorable and distinctive is that it is Cassandra’s voice exclusively building the world, telling the story. Every time a derivative tango or Charleston invades the stage, though, it’s clear that the writers have abandoned Cassandra’s sweetly eccentric musings for a blander, grander sound. And because Cassandra gets too often left behind, the varied complexity of her thoughts ends up replaced by the ultimately uninteresting romantic plotline her writerly mind embellishes and retrospectively re-crafts.

It’s not that Smith’s novel isn’t song-worthy. I Capture the Castle, directed here by the Palace Theatre’s Artistic Director Brigid Larmour, centers on the family of reclusive author James Mortmain (Ben Watson), who lives in a run-down English castle and whose lives are upended by the arrival of a pair of wealthy American brothers, potential suitors to the Mortmain girls. Cassandra’s rocky road to womanhood, the sudden discoveries of love and lust, and the mistily evocative depiction of the castle and its surrounding landscape should recommend themselves for a tuneful re-imagining. We can hear that potential in Edis’ quirky, dissonant setting of the book’s opening lines, a musical motif that repeats effectively throughout whenever Cassandra writes in her diary. The need for music also feels evident in the 11 o’clock number, a fiery confrontation between Cassandra and her father. Otherwise, though, the songs tend to weigh down a book-heavy show, neither deepening our understanding of the characters nor lifting their experiences above the quotidian plane, a feat that Smith’s poetic prose so deftly accomplishes.

Occasionally, that disconnect stems from characters being rewarded with musical introspection they haven’t earned, like a well-sung but one-note power ballad in the vein of “As Long As He Needs Me” for the Americans’ underdeveloped aunt Leda (Shona White). Most of the time, though, Edis leaps at any opportunity to evoke the 1930s through endless Charlestons, tangos, and beguines which seem pasted in, without attention to character, like the scores of the very earliest Gershwin or Rodgers & Hart musicals.

It’s Irving Berlin who gets an extra-special shout-out, though, in the form of a bewildering production number early on that textually conjures “Blue Skies” while musically pilfering from it: “There’s sunshine in my champagne,” the cast sings, in defiance of the British weather, while Charleston-ing manically.

Howard’s lyrics are competent and never cringe-worthy but tend towards the obvious. “Not quite a woman/Not still a child/Feeling in limbo/Running so wild,” Cassandra sings in the opening number, and while Smith’s narrator is also impressively self-aware, this rendering feels rather more like telling than showing.

Happily, though, there are plenty of good performances and strong voices among the nine-actor cast. Lowri Izzard nicely captures Cassandra’s innocence and, when the script makes space for it, wryness. Kate Batter as Cassandra’s sister Rose, Luke Dale as the younger American brother Neil, and Isaac Stanmore as Cassandra’s beleaguered country-boy suitor Stephen stand out vocally. Perhaps the talented Suzanne Ahmet as the girls’ free spirit stepmother Topaz does the most successful work in harnessing the energy of Dodie Smith’s characterizations, balancing between persuasively tender and delightfully nutty.

Ti Green’s design also captures the castle with panache: chairs hang off ladders and winding stairs lead to gargoyles in this twisted, clever set.

“I mean, everything is already created by the first cause – call it God, if you like,” Simon tells Cassandra in the novel’s final scene as they discuss her father’s literary work. “Everything is already there to be found.” There’s music at the heart of Dodie Smith’s I Capture the Castle, but it hasn’t quite been found yet.

I Capture the Castle is playing at the Watford Palace Theatre until April 22.

Photo: Richard Lakos