Imagine if "Forrest Gump" began with 30 minutes about shrimp fishing and you'll see the first issue with Tom Hanks' "The Making of Another Major Motion Picture Masterpiece."

The Oscar winner's debut novel opens with a prologue followed by 80 pages about uneventful life in a Northern California town where a young man meets his drifter uncle, a hero in World War II. Not much happens, so the long second chapter in "Masterpiece" may make you think, "Why am I reading this?" and "Where's the 'motion picture' stuff?"

It's in the third chapter, it turns out. There is a reason Hanks devotes so much space to the young California man. He writes a comic book based on his uncle and that comic (reproduced in "Masterpiece," with illustrations by R. Sikoryak) will provide inspiration for "Knightshade: The Lathe of Firefall," the "major motion picture" whose making is chronicled in the remaining 300 pages of the book.

The trouble is that Hanks is guided by an actor's instincts, not a writer's. Actors want to know everything about the people they play: what happened to them as kids, what scares them, when they've felt lonely, what their favorite Christmas present was. Keeping those details in their heads helps them create characters, even though audiences never know the details because they're not in the script. But that "not in the script" is important.

In "Masterpiece," Hanks includes all of that back-story stuff — he's constantly introducing minor characters, only to dive back into their childhoods — and most of it feels extraneous.

That, readers, is why skimming was invented.

Because the rest of "Masterpiece" will have tons of appeal for anyone who wishes that they could visit a movie set but has never snagged one of those special lanyards that tells them they belong.

From the meetings in which resourceful director Bill Johnson and his faithful team envision the movie to its premiere at a huge theater in Manhattan that seems modeled on the Ziegfeld (see what I mean about an extraneous detail slowing down the written word?), "Masterpiece" lays out, day by day, how movies get made.

The short version is: "There are problems and you solve them." Movie directors are always saying their job is to answer questions all day but "Masterpiece" shows what that means. Johnson's "Knightshade" faces the kinds of setbacks many movies do: An actor misbehaves, another actor disappears, unexpected costs mount. And Hanks shows how clever people solve those problems. (The fictitious "Knightshade" is meant to be a side entry in a series of superhero movies like the cinematic universe of Marvel, which is dubbed Dynamo here, and it's being made for a Netflix-like company called Hawkeye.)

That stuff is entertaining, guided by Hanks' verbally dexterous humor, knowledge of film and idiosyncrasies. For instance, "Masterpiece" is obsessed with typewriters, which are mentioned more than 30 times, a detail that makes sense if you remember Hanks wrote a book of short stories inspired by his own vintage typewriter collection.

It's easy to imagine the actor directing a movie of "Masterpiece" (he could play Johnson, too). That would give him a chance to solve some of the storytelling problems he created for himself.

The Making of Another Major Motion Picture Masterpiece

By: Tom Hanks.

Publisher: Knopf, 436 pages, $32.50.