The Decemberists, Royal Festival Hall, London

With their "Chimbley Sweep" and "Shanty For the Arethusa", The Decemberists are the ultimate escapists, finding fertile ground in traditional folk themes, peppered by Dickens's Victoriana and CS Forester's Hornblower novels. Not your typical US indie rock, then.

But this five-piece hail from open-minded Portland, Oregon, where leader Colin Meloy has found a home for his time-travelling, globe-trotting lyrical style and for a band named after an obscure 19th-century Russian officers' uprising.

The bespectacled Meloy looked more suited to library studies than engaging a crowd. Yet The Decemberists' vivacity meant you felt every thrust, and the Festival Hall's pin-drop acoustic was perfect for their intricate compositions that started from a solid roots-rock base, then added flourishes that brought to mind anything from sea shanties to Kurt Weill.

Their fourth album and major label debut The Crane Wife, inspired by a Japanese folk tale, is their most ambitious work, with two long tracks made up of distinct parts. Such suites were among the most memorable sections of the night. The album's title track saw the group at their lively best. Even better was "The Island", where they morphed from Led Zep acoustic baroque through a rampaging "Whiskey In the Jar" to end with a macabre lullaby. They were just as effective on more straightforward numbers, especially the winsome "Yankee Bayonet".

Yet at times the band struggled to make the step up from the student circuit. Throwaway number "The Apology Song", written to say sorry for losing a mate's bike, was charming but not strong enough for the venue. Meloy rambled between songs as he tried to connect with a seated crowd, and was self-conscious when he moved stage front. When the band were in high drama mode, you could ignore his limited reedy vocal, while on simpler songs, noticeably the bland latter Stones rocker "Perfect Crime 2", he failed to inject sufficient emotional vim.

The Decemberists' party piece has them focus their art on one, snaking tale that had us hooked from unlikely opening to the finale in the belly of a whale. Meloy spins a ripping yarn.