This achievement is for finishing Chapter 10: Rust. Here is a 100% walkthrough including all the secret locations and the missable achievement
Reckless.
Secret / Collectible #1 - 0:34
Secret / Collectible #2 - 1:25
Secret / Collectible #3 - 2:09
Secret / Collectible #4 - 2:58 (Reckless)
Secret / Collectible #5 - 3:04
The Reckless achievement in Unravel worth 87 pointsFind the secret in the engine room