Like any other kind of fiction, authors of science fiction or fantasy are often advised to begin in medias res, and like any other kind of fiction there are plenty of exceptions. Some stories that start well before the “interesting” parts tend to drag as a result: I know I'm not alone in finding Harry Potter and the Sorcerer's Stone impossible to get into at first read. And that's with a “mere” decade gap or so between the opening chapter and the main plot; writers of epic fantasy can have millennia go by between the prologue and chapter one, as is the case for The Wheel of Time.
It's also the case for the Stormlight Archive, Brandon Sanderson's new epic fantasy series. But when I read the first book, The Way of Kings, I didn't mind the long gap between the “Prelude” to the entire series and the extra “Prologue” to book one of ten; while it's unsurprisingly not clear how it all fits together, I'm sure that the rest of the series will fill it in in time.
What did frustrate me, however, were other jumps in time throughout the book. Chapter One describes a battle; Chapter Two, eight months later, picks up with Kaladin, one of of the combatants from the battle, by then a slave. The narration of the book is third-person limited, with many parts from Kaladin's perspective but other chapters from other main characters. However, we see Kaladin not only in these chapters, but also as a younger person. The flashback chapters (where he goes by his nickname, “Kal”) take up a large chunk of the book. By the time we get all the way up to the battle from chapter one, it's already page 825, and we're not done yet; although it's not an offset chapter, Kaladin has another mental flashback starting on page 1148.
I understand that writing all the events in chronological order (first Kaladin's childhood, then more contemporary happenings interspersed with other people's perspectives) would have been jarring. After chapter after chapter of nothing but Kal, suddenly throwing many more characters into the mix would be off-putting for some readers. But having so many flashbacks wasn't the most enjoyable structure either. The events remembered on page 1148 are clearly important to Kaladin, who obsesses about preventing something similar from happening again throughout most of the book (with limited success). But keeping the outcome of the battle secret from us felt like a cheap way for the author to artificially introduce tension.
The “artificial tension” of in medias res gone bad is even more striking in Robert Sawyer's science-fiction novel Frameshift. The novel opens with its main characters in its main setting: Pierre Tardivel and Molly Bond in 1990s UC-Berkeley, where they both work. “Pierre didn't like Molly walking home alone at night,” we learn, so he tries to walk her home. But on their way, Molly, who is psychic, reads the mind of a nearby criminal who has been hiding and waiting to kill Pierre on the orders of a mysterious “Grozny.” Thanks to her preternatural warning, Pierre is ready to defend himself, and the police show up and reveal that the criminal is a neo-Nazi with a track record. Pierre and Molly go home together, and we learn while they share a bed that Pierre will “probably be dead soon anyway.”
The prologue is no doubt designed to hook the reader; here in 2,500 words we have telepathy, a potentially neo-Nazi conspiracy, romance, and a lingering death sentence. Chapter One, however, begins in August 1943, where Nazis carry out atrocities. No science-fiction anything. Chapter Two is, very clunkily, set in “The early 1980s. Ronald Reagan had recently been sworn in as president, and, moments later, Iran had released the American hostages it had been holding prisoner for 444 days. Here in Canada, Pierre Trudeau was in the middle of his comeback term as prime minister, struggling to bring the Canadian constitution home from Great Britain.” The beginning chapters jump like that from character to character and setting to setting, with no pretense of cohesion. And if I had read the first chapter without knowing the book's place on the science fiction shelf, I probably would have put it down; it displays none of the close interpersonal relationships, often with some illness for one party, sense of mystery at the order within the universe, or more Canadiana than you can shake a hockey stick at that I associate with Sawyer.
So, in that sense, the prologue did its job in encouraging the readers to stick with it because something plot-like was on its way. (Pierre and Molly, it turns out, were married before the prologue; was the author expecting people with different last names in bed together to be more titillating for the readers?) But in another sense it's kind of a cop-out; the fact that the beginning is so disjointed that it relies on the prologue to do all the work is not a credit to the prologue, but rather a flaw of the first two chapters.
Another part of the problem is the scope of the book. “In 1990s Berkeley, a terminally ill biologist obsesses about winning the Nobel Prize...and fights Nazis!” seems like it could work as the summary for a novel that had no science-fiction elements of any sort. “By the way, his wife is telepathic and their daughter is <spoiler alert>” seems to make it almost too busy.
On the other hand, in the 1200-page The Way of Kings, there's plenty of ground to cover even without the flashbacks. Brandon Sanderson has said that every book in the Stormlight Archive will feature more flashbacks; mostly for other characters, though Kaladin might get a repeat. So I'll have to get used to the structure, like it or not. In that case, however, I think I can put up with it; even without the flashbacks, the normal “present-day” story is relatively compelling on its own.