Suddenly the "prairie harpy" blurts out that there's nothing wrong with the grav boot. The prairie harpy then finishes putting on her prairie floral gown and turns around so we can all see that she's actually Kaylee. That's certainly an unexpected development. Mal stares at her, and she waves hello. She's got pigtails. Yuck. Of course, it looks bad in part because she was just on the floor having sex. A confused Ty XXXVIII is dismissive of Kaylee. Kaylee insists that she saw what the actual problem was while the two of them were having sex. That certainly doesn't say much for Ty XXXVIII's prowess, does it? Kaylee insists that it's something called a "reg couple." Ty XXXVIII doesn't even know what a reg couple is. Kaylee bends down under the engine and does some fiddling around. In about ten seconds, she's got the engine running again. Ty XXXVIII doesn't even understand what she did. Mal asks Kaylee how she learned how about engines. Kaylee explains that her dad always said she had a natural talent. Hey, I think Kaylee's got a non-evil dad! It's a brave new world for Mutant Enemy. She exposits that she works down on the farm for Daddy when he's got work. But there hasn't been much work lately. Mal asks her if she's got much experience with these ships. Kaylee admits that she's never even been up in a ship before. Mal asks, "Wanna?" Kaylee realizes that she's been offered a job. She wants it, but she has to go ask her parents first. She rushes off. Ty XXXVIII asks what Mal needs two mechanics for. Mal says, "I really don't," as he walks out. And that's how Serenity traded the Ty of the future for the Amy Wynn of the future. And the ship is the better for it.
Oh, where are we now? We're back at the post-accident scene. Mal finds Kaylee in the engine room, just sitting there, staring at a broken doodad. Kaylee's sulking in guilt, thinking that she should have known there was something wrong with the ship, and she worries that she wasn't paying enough attention. Mal tells her that they don't have time for brooding; she needs to get the engine running. She says she needs a new catalyzer. Mal says they don't have a new catalyzer. I would point out the folly of traveling through the vacuum of space without any replacements for vital parts of your engine, but I think the point here is that they don't have the luxury of spending money on stuff like that. Kaylee insists that the catalyzer they've got doesn't work anymore. Mal leads Kaylee over to the engine turbine so she can show him where the part goes. She shows him, but because of the damage, it doesn't fit anymore. And without it, the engine doesn't work. And without the engine, they don't breathe. And without breathing, they don't live.