Swiss folk-metal act Eluveitie's fifth album is a concept record based, as the title suggests, around the Gallic Wars from the perspective of the ancient Helvetii -- the Celtic tribe that occupied modern Switzerland before being annihilated by Roman legions. Eluveitie's unique selling point has always been their mixture of Scandinavian death metal with a variety of traditional Celtic (mainly Irish) folk influences. However, while the use of tin whistles, fiddles, bagpipes and, most recently, the hurdy-gurdy has given their music an added dimension, they too often comes across as a straightforward modern metal act with gimmicky Celtic metal trappings, and the folk sections appear tacked on. Helvetios, the title track and opening track proper, does little to bat against this notion -- a mournful piped melody quickly gives way to generic thrash riffing and coarse death growls, and very little attempt is made the integrate the contrasting styles. This pattern continues for much of the album, with generic melodeath efforts like "Home" and "Meet the Enemy" battling for space with more sedate folk numbers like "Scorched Earth" and "Hope." However, when Eluveitie do get the balance right between their death and folk personas, the result is vibrant and infectious. "Luxtos" and "The Siege" are hugely dynamic tracks that blend highly melodic pipe and violin melodies alongside thrashy riffs and Chrigel Glanzmann's rangy death growls. Hurdy-gurdyist Anna Murphy has lent vocals on previous records, but here she takes center stage on two of the album's stand-out tracks, "A Rose for Epona" and "Alesia," the former in particular showcasing her full dynamic range and wonderful tone. Still, over 60 minutes and 15 tracks, Helvetios is an inconsistent and meandering listen that doesn't quite do justice to the ambitious concept it attempts to invoke.