One of the elite group of hip-hop outfits - Beastie Boys, Public Enemy, OutKast - whose albums figure in the collections of those who otherwise give rap the widest berth, The Roots' growth from their 1993 debut 'Organix' to now has been the fascinating story of what happens when you turn a genre inside out.

'Game Theory', their first album for new label Def Jam, finds them in dark mood. From its stark cover and opening lyric - "America's lost somewhere inside of Littleton/11 million children are on Ritalin" - this dense record offers little in the way of good times, instead working as an anger-filled State of the Union address.

In a career of highlights, some of The Roots' best moments are here - their collaboration with hometown Philadelphia legend Bunny Sigler on 'Long Time' is an instant favourite while the all-too-short 'Baby' puts an irresistible guitar hook on a story of fatal infidelity.

Elsewhere, The Roots sound at their scariest on gangster chronicle 'The Music', pay an epic farewell to the late producer and MC J Dilla on 'Can't Stop This' and offer up 'Bread and Butter', a bonus track with a great earthy groove that should've featured far more prominently in the running order.

And when even your bonus tracks are better than what many outfits put on their albums you have to wonder just how much higher can The Roots keep raising the bar for themselves.

Harry Guerin