We all owned one. My 1970s-era View-Master was red plastic with white trim, and the reels my parents bought for it tended towards the G-rated and Disneyified — Cinderella, Bambi, maybe an occasional visitor from the Krofft Super Show. (Why were those other sea monsters so mean to Sigmund?)

But my sister, 18 years older than me and the mother of my three nieces, was a young stay-at-home mom on a limited budget who haunted garage sales like it was her job. Her kids’ View-Master reels were as eclectic as the neighbors who sold them. It was through her collection that I learned View-Master also cranked out reels for travelers (See the castles of Belgium, or the wild animals of Africa!), for scholars (Learn about the United Nations, or the moon landing!), for collectors (Rare coins! Famous stamps!), and a few that defied classification. (The Guinness Book of World Records reel features the world’s fattest twins riding motorcycles. Bless and damn you, 1970s, we shall not look upon your like again.)

This varied library makes more sense once you learn that the View-Master wasn’t invented to be a child’s toy. No group of suit-wearing project managers seated around a conference table came up with the concept, and it wasn’t focus-grouped and marketed to within an inch of its life. The plaything that ended up in the bottom of so many of our toy boxes next to random Monopoly cash and Barbies has a history, and no one knows it better than Gretchen Jane Gruber, whose father, William, invented it.

Gruber’s book, View Master: The Biography of William B. Gruber, may disappoint those looking for a quick and light reminiscence about a favorite childhood possession. The title doesn’t lie — it’s a biography of a man, not of his invention. Gruber makes that clear from the book’s cover — an image not of the toy, but of her father as a young man in the Oregon mountains in 1928 — and from her introduction, where she notes that the View-Master itself has been extensively written about elsewhere, and states that this is not that story.

If William (originally Wilhelm) Gruber’s life were depicted on a View-Master reel (psst, Gretchen — possible book tie-in idea!), the first photo would be a travelogue-style image of his idyllic Munich childhood before World War I broke out. Born the son of a blacksmith in 1903, he acted out fairy tales in the Black Forest, witnessed Halley’s Comet, and attended a performance by the great Harry Houdini.

But when Gruber was 11, World War I broke out, with Germany at its bloody center. Click to the second shot, of a teenager whose once-clear future was now a muddle. Due to wartime food deprivation, Gruber’s family realized he did not have the strength to follow his father into blacksmithing, and would need to find another career. Despite a failed early photography apprenticeship, the lure of the camera called early to Gruber, and he became fascinated with stereoscopes, small devices that let users’ eyes meld two separate photographic images into one 3-D view. You know where this is going.

Although the View-Master’s inspiration arrived early in Gruber’s life, it quickly receded into the background. For years, Gruber kept photography only as a beloved hobby, stumbling instead into a career in piano tuning. He struck a lucky chord with that path. His skills would eventually lead him to settle in Portland, and connections he made there would help create those familiar toy box icons.

But a Gruber biography reel would also include an unnerving photo — the inventor as a young Nazi. Gruber joined the Nazi party in 1921 and passionately believed Adolf Hitler could save a troubled Germany. He was proud to have seen the German dictator in person, and as a young man, believed that Jews and communists were coming together to try and take down his homeland. His involvement with pro-German groups in Portland eventually led to an FBI investigation that exiled him to Idaho while his case was investigated. The case is eventually closed, and Gruber himself seems to have untangled his love for Germany from his feelings about Hitler, keeping his national loyalty while learning to his horror that the leader he once supported was history’s greatest madman.

Until the Nazi threads begin to wind through the story, it would be easy to dismiss “View Master” as a daughter’s pet project, the tale of one man’s childhood, career, life and loves, of interest to his family members only. But Gretchen Gruber doesn’t flinch from the uncomfortable truth of her father’s beliefs. Drawing upon William’s extensive family diaries, letters and histories, she’s able to sketch out the world in which a young German man could find himself knowing just enough about Hitler to convince himself that the Third Reich brought hope, not horror. It’s a deeper and more nuanced picture than any View-Master image could produce.

Once Gruber’s battle with J. Edgar Hoover is over, the tale of the View-Master itself hitting the market is rather dry by comparison. As a ‘70s and ‘80s obsessive who’s written two pop-culture encyclopedias, one of which contains a View-Master entry, I was less interested in Gruber’s family life, and would’ve appreciated details on how two-hour Disney films were condensed down to a dozen or so View-Master images, or which reels were the most sought-after. But I can’t say I wasn’t warned. This is a book about the inventor, not the invention.

Yet stick with it, and you’ll learn that Gruber had high aspirations for his invention, many of which he achieved. Even as he was being investigated during World War II, the U.S. government was utilizing View-Master technology to train naval aviators. In partnership with a surgeon, Gruber worked tirelessly for a decade to produce a 25-volume View-Master 3-D guide to the human body that was a boon to medical schools. View-Master made him rich, but he was never happy to sit back on the ocean of cash made from cartoon-loving kids like me.

Was William Gruber himself as colorful and interesting as his invention, lively enough to warrant a 300-plus page book? That depends on what you’re looking for. Not every View-Master reel delivered animated animals, as I learned from my sister’s garage-sale finds. Sometimes, the toy took you on a quieter, more educational tour.