Here's the thing you gotta know about Blake Crouch.

You remember that guy from college, sophomore year? The one that was always there at the bar, on the strange nights when it felt like you could hold off last call just by talking fast enough and thinking big enough? He was the one you'd find yourself listening to at 3am, sitting on the floor, weed and cheap beer twining together in your head as he spun out some bonkers theory about perception, psychology, memory, reality. The one who never seemed to sleep. Who always said the most fascinating things.

Blake Crouch was that guy.

I mean, maybe not. I don't know him. Never met him. But he was that guy. Is that guy. That's how he makes his nickels now. Being that guy, over and over, his books like a perfect distillation of all those late-night, chemically altered conversations that seemed so important once upon a time.

And his new book, Recursion? Man, it's a good one.

It starts like this: It is 2018 and NYPD detective Barry Sutton fails to talk a jumper off a ledge. Ann Voss Peters falls 40 stories to her death, but just before she does, she tells Barry that she is suffering from False Memory Syndrome — an emerging neurological disease in which sufferers are suddenly afflicted with vivid, encompassing memories of lives they never lived. There are other spouses, other children, other choices made — sometimes better, sometimes worse. The memories come on in grayscale, black and white but with the full weight of actual memories. For some, the dissonance drives them to suicide.

Then it is 2007. Scientist Helena Smith is approached by representatives of Marcus Slade, one of the richest men in the world, who is offering to fund her research into memory and Alzheimer's care.

It is 2018. Barry is visiting his ex-wife on the birthday of their daughter who died in a hit-and-run accident years ago.

It is 2007. Helena is helicoptered out to an off-shore oil platform that Slade has turned into a laboratory for her. He tells her they are going to change the world.

It is 2018. Barry has some concerns about the Peters suicide. He begins investigating. He finds a secret hotel, a doorway underground ...

And you think you know where this is going, right? Only you don't. Not even a little. Because what Crouch has made here is a puzzle box time-travel story, all based on memory and death. He has sketched out the rules for a new reality where people can go back and re-live their lives, fully cognizant, in an alternate timeline. Where they can get a do-over and make different choices.

But there's a catch. A big one and a clever one with some weird modern resonance. And it is the unforeseen consequence of this catch that provides the hook for Recursion.

No, I'm not going to tell you what it is. Where would the fun be in that?

I will tell you that Crouch handles the build-up well. That he juggles the multiple narrators and timelines with a confident economy. He couches the occasional (necessary, sometimes fascinating) infodump in character and tension most of the time, only rarely resorting to flashbackery or moody staring-off-into-the-rain soliloquy. And even though some of his relationships come with a whiff of plot contrivance, he has always been rare among that cadre of speculative fiction writers who traffic in big, near-future ideas in that his characters, on an individual basis, come off as actual humans rather than robots programmed to spout off dialogue.

Barry is believably damaged, even years later, by the losses he has experienced. Helena reacts with a unique combination of human panic and intellectual, scientific rigor when confronted with what she has helped Slade to create. And even Slade — a character so destined for one dimensional villainy that his name is Slade, for f*@&'s sake — gets an odd sort of humanity thrust upon him by Crouch. He's a guy who thinks he is doing good. Who is forcing humanity to confront its own limitations by offering a way to transcend them. But still, his name is Slade and he has a secret mad-scientist lab on an abandoned oil rig in the middle of the ocean, so.

Anyway, Crouch? Certifiable midnight weirdo. Absolutely that guy who wonders what would happen if people were suddenly actually given the ability to travel through time, and then keeps his friends up too late fiddling with the details, asking, Okay, but what about the janitor in that building? What about the people down the street?

Recursion is his answer to all those questions. His theory, fully worked out on the page. It is fuller than you'd expect. More fleshed. More human. It has a thrumming pulse that moves beyond big ideas and into their effects on a larger, more complex world. I mean, if you had the chance, is there some moment in your life that you'd want to go back to? To take another crack at, knowing everything that you know now?

Of course you would. But Recursion doesn't just ask you to consider the power, it wants you to see the consequences. All of them. It wants you to see the damage that travels in the wake of such choices. The bodies. The nightmares.

And then it asks again: Still, knowing what you know now ... would you?

Jason Sheehan knows stuff about food, video games, books and Starblazers. He is currently the restaurant critic at Philadelphia magazine, but when no one is looking, he spends his time writing books about giant robots and ray guns. Tales From the Radiation Age is his latest book.

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