Fred Frith has dedicated a good part of his energies over the last few decades to extending the possibilities of the electric guitar in an improvising context. In live performance, he'll often play the instrument face up on his lap, using various brushes, ball bearings and other tools to coax wildly varied sounds and textures from the strings. He's also developed an extremely subtle approach to incorporating electricity into his extemporisations, folding in delicate pedal swells and ebow drones. Faced with the sheer variety and unpredictability of Frith's palette, saxophonist Lotte Anker sounds like she's playing in a state of heightened consciousness – responding and commenting with synaptic swiftness and an impressive range of trills, peeps and blurts. By contrast, the hefty physicality of Barry Guy's double bass insists on setting the tone, delineating a sturdy wood-and-metal tactility to his duets with Frith. There's a wonderful sense of unfettered freedom in these pieces, allowing Frith and Guy to wander into moments of mutant folk, insectoid immediacy and lugubrious dirge. Taken together, these two sets provide a convincing portrait of elevated imaginations at play.