Purpose/audience: Designed artefacts intended for users and markets serve primarily functional and pragmatic uses, yet there are other forms of designed artefacts whose purpose for being is to present concepts, inspire thought and provoke action. Their existence is not utilitarian but one of speculation. In this article, we draw attention to how materials, technologies and ideas are brought together in speculative forms of editorial design that confront the existential crisis of our times – the climate emergency. In doing so, we aim to catalyse future work on hybrid print-digital books and design for activism. Methodology/approach: Through a critical reflection of the process of designing, developing and publicly exhibiting an interactive book-of-the-future centred on a contemporary environmental issue, we interrogate the design of multimodal, polyvocal artefacts and their place in public and academic discourse. We briefly explain the origins and motivations of the project to create The Climate Domesday Book, analyse the design and production process and critically review both the physical book design and the digital texts within (films, poetry, art, performances and writing). Findings: Manifest as a printed-digital speculative artefact, The Climate Domesday Book is a diegetic prototype of the book-of-the-future, a knowledge-building artefact through graphesis and a discursive design that stimulates thought and action. Temporally and conceptually, it shifts its mode of existence from an ambiguous project towards a generative design and – eventually – a design for activism. The collaborative design of discursive artefacts can play a part in shaping public understanding and discourse on critical issues. Such artefacts facilitate new social connections, provoke individual action and serve as catalysts for social and technological innovation. Implications for practice, society or research: Functionalist or utilitarian forms of design – products, processes, services and built environments – are prevalent in everyday life, yet these do little to advance our thinking about possible, desirable or alternative futures. By contrast, multimodal, polyvocal activist designs afford designers and users/readers/publics the opportunity to interrogate contemporary (and persistent) issues of human concern in imaginative ways and provoke positive action in response. Originality/value: Our ‘book-of-the-future’ draws attention to the possibility of hybrid print-digital publications as lean-back/stand-back and lean-forward/step-forward discursive and activist devices in either public or private spaces, as alternatives to agonistic street demonstration or direct action and as exemplars of aesthetic, activist energy humanities.