Only the Brave is the very first musical produced by the Wales Millennium Centre and this week's premiere appropriately stars Welsh musical theatre names Caroline Sheen and David Thaxton. It's a show that has been in development for some time, with a previous run at the Edinburgh Festival some years ago. Now produced as a large-scale show, Only the Brave is set in 1944 when a dangerous mission behind enemy lines is key to success for the D-Day landings – the most significant invasion for the Allied Forces during the Second World War. Like the more famous 'war' musicals before it, Only the Brave's themes of love, friendship and hope make for an emotional evening which is ultimately worth investing in.

Composer Matthew Brind and lyricist and director Steve Marmion’s new musical shows the courage and determination of those who fought in the Second World War and the human spirit and determination of characters and stories which are inspired by true events. Writer Rachel Wagstaff – who adapted the tremendously moving Birdsong on stage a few years ago – ensures that the story of Only the Brave is well balanced between the men who were in the line of fire and the women back at home. Women like Caroline Sheen’s determined and stoical Joy Howard, who were busy playing their own important part in the war effort, whilst also hoping that their loved ones would return home safely. Some women put their life on the line too – Nikki Mae plays a character of Eponine type endurance, a young French girl working in a café who wants to make a difference, leaking information to Helen Hobson's Madame Vion in order to help the Allies.

The long first half still feels very much like a work in progress with story and characterisation slowly developed. The opening scenes are confusing at times as lots of characters are introduced and there is a series of very short scenes which switch very swiftly. The music is through sung a lot of the time, with characters coming on at times singing songs with no context given beforehand. In the second preview I attended, there were some staging issues (with lots of large steps being hauled around the stage awkwardly) and some sound problems in the ensemble scenes which I'm sure were ironed out by opening night. However, the first half comes to an exciting conclusion with the first real showstopper of the evening, 'Band of Brothers', which is later reprised at the end of the show.

The second half is much more powerful – the storytelling is a lot clearer and I actually felt for the characters and empathised with their plight. There are some impressive effects too, and projections are used more effectively as part of the staging, as David Thaxton’s Captain John Howard leads a battalion of men to capture two bridges over the River Orne. Musically there is more variety too, with a song about British favourite, 'Cuppa Tea', breaking up the tension, and the poignant 'Regret and Sympathy' again giving the women’s side as they receive bad news about the fate of certain men. The powerful finale to the show looks like something from the barricades of Les Mis itself, and the involvement of a real life veteran as the older John Howard (David Webb at the performance I attended) brings the humanity of the situation even closer to home.