The Grand Tour, Finborough Theatre

Everything about this little-known and largely forgotten show suggests epic, starting with the title: multiple locations, ambitious concept, big ideas. But like so much of Jerry Herman's work - and the received wisdom on it is invariably wide of the mark - The Grand Tour is a chamber piece at heart.

Adapted from the Franz Werfel play Jacobowsky and the Colonel, the show focuses on a  Polish Jew, Jacobowsky, and an anti-Semitic Polish Colonel, Stjerbinsky, who are thrown together in a desperate flight across France from the fast-advancing Nazi tsunami.

Their eventual bonding - brought about by the selfess widom of Jacobowsky, the little man with the big heart - is something that Herman and his book writers, Michael Stewart and Mark Bramble, could strongly relate to. For Herman, it was another chance to write his aspirational Jewish musical, his first having been Milk and Honey in 1960. The Grand Tour made it to Broadway in 1979, with (Tony-nominated) Joel Grey, and lasted 61 performances. It didn't help that Sweeney Todd opened the same season.

And maybe this is where the misconceptions about Herman are thrown into even higher relief. He's always been dubbed "the showman" - the old-style Broadway glitz-monger with his marching songs and big walk-down numbers. But in the sometimes painful honesty of his ballads lies real craft and sophistication (though never artful, which is what Sondheim always is), and in a score like The Grand Tour one is reminded how all the catchy Hermanisms are closer to the popular music of Eastern Europe than to Tin Pan Alley. (The ensemble is pictured above)

Part of the charm of the score is that these tunes naturally have nostalgia written into them. OK, so there are some hokey lyrics alongside the home truths, but a little miracle of memorable simplicity like "Marianne" (a song given a conspicuous afterlife by Michael Feinstein) comes from the musical imagination of a very gifted melodist. Then there is the way he places that number alongside Marianne's "I Belong Here" - songs of loving and belonging back-to-back. And the wistful wit of "Mrs Jacobowsky", which is a cracking number by anybody's standards.

Alastair Brookshaw plays Jacobowsky with wonderful engagement and truth in a show that finds every character and scene barely one step ahead of the advancing but - other than one SS Captain - unseen Nazis. On the tiny postage-stamp stage of the Finborough, the director Thom Southerland and his designer Phil Lindley use their ingenuity to open up little windows and doors from the fabric of a map of Europe, relocating us by suggestion whilst using sound to establish the proximity of the advancing aggressors. There's a train journey where the scenery is literally passed hand-to-hand; there's the somewhat clunky metaphor of the circus, which the writers use to headline the notion of doing "One Extraordinary Thing"; and, of course, there are nuns, The Sound of Music having long before ensured that it was open season for them in all subsequent musicals involving Nazis. 

But for all the creaks and cracks in the fabric of the show, the darkness is still there to envelop us and that final scene between Brookshaw's Jacobowsky and Nic Kyle's unflinching Colonel does get to one. "You, I Like" is the simple sentiment of the song, but through it and the dialogue that follows we feel Jacobowsky's eternal solitude: the wandering Jew, the outsider always in the wrong place at the wrong time.

One for collectors.

• The Grand Tour is at the Finborough Theatre through 21 February