1141 Science 12 JUNE 2025 B ritish nature writer Robert Macfarlane’s ac- claimed writings pivot around themes of language and landscape and their enduring legacies in myth, literature, and memory—or “matters of the human heart,” as he puts it (1). In 2019, Macfarlane published Underland: A Deep Time Journey, which took a darker turn. A bestselling work of transcen- dent beauty, Underland is a tale of personal adventure that explores and complicates humanity’s relationship with subterranean spaces, the ephemeral nature of time and place, and, perhaps above all, the fragility of all we are and all we create. The film adaptation of Underland premiered on 5 June 2025 at the Tribeca Film Festival. Poetic and mesmerizing, the film echoes the book in many essential ways, but it follows different storylines. It will resonate with readers of Science for focusing on the work of three intrepid researchers: Fátima Tec Pool, a Mexican archaeologist; Bradley Garrett, an American geographer; and Mariangela Lisanti, an American theoretical physicist. Underland joins these scientists underground to shine a light on their daring quests for knowledge. It may seem paradoxical—that darkness is a medium for vision, a means of insight—but it is effective. After all, the verb “to understand” hints at the importance of passing beneath something to comprehend it. The 20th-century scholar Joseph Campbell argued that stories everywhere recount adventurous rites of passage, following a nar- rative structure known as the hero’s journey (2). His template was complex, involving 17 events organized into three main stages, but he summarized the basic pattern as follows: “A hero ventures forth from the world of common day into a region of supernatural won- der: fabulous forces are there encountered and a decisive victory is won: the hero comes back from this mysterious adventure with the power to bestow boons on his fellow man.” Germane here is Camp- bell’s characterization of the middle stage as an “inmost cave” where heroes battle with “powers of darkness in order to return with the gift of knowledge.” Underland ventures into several inmost caves, both real and met- aphorical. The first is a vast limestone cenote in Mexico. It invites comparison with Xibalba, the Mayan underworld, and the scene of many adventures in Mayan mythology, especially those of the Hero Twins Hunahpu and Xbalanque. Another inmost cave is a 200-mile labyrinth of storm drains beneath Las Vegas, a refuge and lair for hundreds of marginalized people. Built to accommodate sudden downpours, the tunnels bear witness to other excesses above, along with dashed hopes and tattered dreams. A third inmost cave is an ultraclean laboratory within SNOLAB, a re- search complex in the operational Vale Creighton nickel mine near Sudbury, Canada. Physicists there work 2 km underground to detect dark matter and understand its physical properties. The film’s scenes from SNOLAB are especially poignant for end- ing in failure; the experiment documented by the filmmakers did not detect a signature of dark matter. Lisanti’s disappointment here is familiar, representing a different kind of inmost cave—one of self- doubt. But our hero perseveres. Impelled by a fear of never know- ing, she asks, “Shall we start again?” although her words are more credo than question. This scene is important. Failure and resolve are essential elements of science; they are success in disguise. But such moments of emotional reckoning are seldom acknowledged by scientists or represented in popular culture, which is a great pity be- cause they are pivotal to every hero’s journey. “Asking why,” muses Lisanti, “is the act of refusing to accept the state of not knowing.” For the final act, the filmmakers visit a sacred space, drawing attention to Mayan rites of passage. The rock walls they capture feature a gallery of extraordinary hand stencils, both positive and negative; and falling on these images are the researchers’ own shad- ows, as if darkness is speaking with the past. As I watched, I could not help but wonder whether this moment of revelation and shadow play was intended as a subtle reference to Plato’s allegory of the cave, a dialogue that equates caves and shadows with ignorance and sunlight with knowledge. Underland certainly underscores the value of light—there are vivid scenes of lasergrammetry and uranium fluorescence—but the central mes- sage is to invert and complicate Plato’s allegory, to call attention to the profound insights that lurk beneath the skin of the earth, where darkness thickens and sounds stir.  REFERENCES AND NOTES 1. R. Macfarlane, Underland: A Deep Time Journey (Hamish Hamilton, 2019). 2. J. Campbell, The Hero with a Thousand Faces (Pantheon Books, 1949). ACKNOWLEDGMENTS This essay benefited from conversations with L. Fannin and C. Hobaiter. 10.1126/science.ady5476 The reviewer is at the Department of Anthropology and the Department of Biological Sciences, Dartmouth College, Hanover, NH, USA. Email: nathaniel.j.dominy@dartmouth.edu PHOTO: COURTESY OF SANDBOX FILMS Underland Robert Petit, director Sandbox Films, 2025. 79 minutes BOOKS ET AL. SCIENCE AND SOCIETY Dark matters A new film celebrates the subterranean Nathaniel J. Dominy Downloaded from https://www.science.org on June 12, 2025