In this swoony sequel to The God and the Gumiho, a trickster god must work with his reincarnated lost love to solve his brother's murder on board a luxury underworld cruise ship.

Seokga the No-Longer-Fallen is working on himself. Reinstated as a god after saving the mortal world from a demon of darkness, the trickster now attends some much-needed therapy. He's also been desperately searching for his lost love Hani ever since the red thread of fate tangled around his pinky finger, signaling her reincarnation. But when the thread leads Seokga to a luxury cruise down the river of the dead, the woman he finds waiting for him isn't Hani . . . she's Yoo Kisa, with no memory of him, and seemingly no interest in regaining it either.

Yoo Kisa is exhausted with her afterlife. While her untimely death wasn't ideal, she hoped the underworld would be peaceful. Unfortunately for Kisa, whoever she was in a past life racked up quite the karmic debt, and now she has to pay it, working thanklessly aboard the SRC Flatliner. Even worse, the red thread wrapped around her pinky followed her into the underworld . . . and although her fated partner has finally found her, he seemingly finds her lacking.

When the Heavenly Emperor is murdered aboard the ship, Seokga and Kisa must solve the heinous crime before the cruise ends. And as the mystery draws them closer together, the god and the gwisin will have to decide what they truly mean to each other. Because there's something bigger at play aboard the SRC Flatliner, something that holds the key to Kisa and Seokga's fated connection-and the very fate of the mortal and heavenly realms.