Studio-recorded in January 2024, Action Theory is the first recording featuring the trio of British improvisers London-based double bassist John Edwards and Cambridge-based Dominic Lash with the Norwegian-born improvising drummer Emil Karlsen who now resides in the U.K. In 2020 Edwards and Karlsen recorded a live album at Iklectik with saxophonist Adrian Northover. In 2021, Edwards and Lash recorded Breach (Spoonhunt, 2022) with saxophonist John Butcher and cellist Hannah Marshall. Spoonhunt is Lash's own label. Completing the circle, in 2022 Lash and Karlsen played and studio-recorded the album Here and Now (Bead, 2023) together with saxophonist John Butcher; as well as playing, Karlsen has been active in revitalizing the Bead label.

Although Lash is renowned as a double bassist, he also plays electric guitar and has gradually been increasing the amount he plays. Breach was one of the first albums on which Lash played electric guitar. Much of his interest in guitar can be traced back to the first Covid lock-down in 2020 when playing together was limited; Lash took the opportunity to explore recordings of himself playing on guitar, and on double bass and make conversations with himself. The results can be heard on the digital album Necessity released in 2021 which Lash dedicated to the recently deceased bassist Simon H. Fell (1959-2020) and guitarist John Russell (1954-2021).

So, anyone expecting Action Theory to feature two basses plus drums should think again as it is a guitar, double bass and drums trio. Studio recorded in London in January 2024, the album comprises five varied tracks ranging in length from 5:34 to 14:40, 47:43 altogether. Straight from the opening notes of "Kinesis", it is evident that this is not improv guitar following in the footsteps of Derek Bailey or John Russell, although there are occasional nods in their direction. Instead, Lash plays guitar in his own distinctive way, one which is highly listenable but constantly changing either in reaction to his own playing or that of Edwards, Karlsen or both. Most importantly, Lash never sounds like a double bassist playing guitar, but a guitarist playing in his own way and enjoying it. Neither Edwards nor Karlsen steals the limelight, both playing in support of Lash throughout. Not only does Lash have a future as a guitarist, he has one with this trio. This is an album which begs to be listened to again and again.