As a fitting successor to their 2013 session Hullabaloo, Challenger Deep is a new creative stage for Riff Raff – the rhythmically tight-wound ensemble led by UK bassist Dave Manington, featuring such local class acts as pianist Ivo Neame, singer Brigitte Beraha and tenorist Tomas Challenger, and now drawing further on their fine balance of collective improvisation and beat-computing ingenuity. Regular road-life has tuned their sensitivities, and on this set of eight Manington originals they consistently hold a balance of quirkily personal conversational intimacy and sharp contemporary-cultural alertness. The casually meandering and then punchily focused wordless vocal opener ‘Dr Octopus’ evolves as Challenger's tenor, Manington's bass and Beraha's spooky whoops intertwine over Giles' percussion hustle. The title-track gently edges soft sax multiphonics into arco-bass swerves, yelpy electronics and then a languidly swaying vocal, ‘The Iliad’ is fast-shifting episodic narrative, ‘Free Spirit’ and ‘Willow Tree’ are graceful vehicles for Beraha's lyrics – with the former also illuminating guitarist Updegraff's skills in apposite countermelodic improv. The group's brusque handling of rhythm-pattern conundrums is driven by the rugged Challenger on ‘Prime Numbers’ and ‘Random Acts of Kindness’, ‘Dangerpig’ is a breathy reverie that becomes a free-blowing, organ-churning thrash. Manington's writing lets his improvising partners flourish in this dynamic outfit, but neither they nor he lose grip on the plot.