Along the route of this sonic road movie, Rob meets people working to protect this extraordinary species: Darlene Burgess, a conservation specialist monitoring butterfly populations at Point Pelee on the shores of Lake Eerie; Nancy Barnhart, coordinating the monarch migration programme for the Coastal Virginia Wildlife Observatory at Kiptopeke State Park, where we also encounter composer Matthew Burtner, whose sonifications of data from the local seagrass beds help track changes in the monarch's environment; and butterfly expert Pablo Jaramillo-López giving a tour of the Sierra Chincua and Cerro Pelón reserves in Mexico. We also hear reflections from the late Lincoln Brower, the American entomologist whose legacy has inspired many of today's research and conservation efforts.

The programme features Rob Mackay's binaural field recordings, and audio from live stream boxes, set up in partnership with the ecological art and technology collective SoundCamp to monitor the monarch's changing habitats. Plus Rob’s own flute playing, recorded in each of the locations visited, also featuring David Blink on handpan and trumpet, and poetry in Spanish about the monarch by Rolando Rodriguez.

Presented and sound designed by Rob Mackay, produced by Andy King.