Megan Boyd was a Scottish spinster who, during her lifetime, was known for mannish costumes, reckless driving and a fondness for bridge. (She once turned down an invite from Queen Elizabeth because there was a game on that night.)

Boyd was a self-taught fly-maker, and we’re told that “people beat a path to her door from all over the world” to purchase her wares. Her flies are repeatedly rhapsodised by the fishers who used them, and her patrons included Prince Charles, who, it is supposed, “had to sit on the same rickety chair” as her other clients.

Yet these small, intricate arrangements of feathers and spun gold – her attention to minute detail is said to have cost Boyd her sight – are just as likely to be found in frames, now highly collectable artworks. Sure enough, there’s a quaint loveliness about her creations that makes one think of the paper engineers who fashion fabulous pop-up books.

Even if you regard fishing as an appalling blood sport, there's a love of craft at the heart of this angling chronicle that's hard to argue with. Behind the camera we find Eric Steel, the former Disney executive (and a producer on Angela's Ashes) whose documentary portrait of Golden Gate Bridge jumpers in 2006's The Bridge made for indelible viewing.

Steel’s return to nonfiction is a lyrical affair, composed of shimmering water, rolling Highlands and swaddling tranquillity. Em Cooper’s swirling, painterly animated inserts are icing on an already pretty cake. Boyd’s former friends, neighbours and customers provide engaging reminiscences and contemplation. She herself appears only momentarily, late in the film, as a flicker from the archives. Her delayed presence works well in a film defined by whispered folk mythologies.

Anglers ponder their pursuit (“escaping into something which anglers feel is the real world”) and recall Boyd with the same mystical awe they use when they talk about fishing and salmon. For these folks, Boyd’s fly-fishes are somehow tangled up with other hallowed mysteries of the sport.

Why does the salmon bother with all those mating rituals? And what does a fish that lives on Atlantic eel want with a shiny fly, anyhow?