WARNING: The following contains spoilers for Season 15, Episode 13 of Supernatural, "Destiny's Child."
The return of Lucifer's prodigal son, Jack Kline, has also meant the return of one of Supernatural's most complicated characters: a soulless Nephilim who's taken the lives of some of the Winchester's worst enemies... but also their own mother, Mary. Still fresh from his resurrection from The Empty by the cosmic tag team of Billie/Death and The Empty's faceless ruler, The Shadow, Jack has been given the unholy task of offing his grandfather, God/Chuck and one hell of a to-do list to get through before he can do it.
In Episode 13, "Destiny's Child," the eponymous child's next mission is revealed to be tracking down the "Occultum." What or where this is is left up in the air -- why makes things crystal clear when the fate of the multiverse is on the line, right? -- but when Jack does get his hands on it, the Occultum restores something he thought was lost to him forever: his soul. And with its recovery, Sam and Dean's best shot at taking down Chuck just became that bit more heroic.
The Occultum, as you'd expect from a key item in Supernatural's final stretch, isn't easy for Sam, Dean, Castiel and Jack to track down. Their first lead comes from Jo, a wayward, conwoman angel, who claims that the demon, Ruby, an old frenemy of the brothers (and an ex-lover of Sam's) hid it in Hell. Despite Castiel warning them against it, Sam and Dean decide to trust Jo's intel and head down under using a spell whipped up by Sam -- who, as he's acting as Rowena's earthly replacement, Dean dubs "Samwitch." They're quickly ambushed by demons under Jo's employ but, upon their return, before they can get on the receiving end of Cas's "I told you so," they find the angel out cold next to a sheepish Jack.
Castiel took it upon himself to get the information they need from the source -- Ruby. So, while Sam and Dean were in Hell, the angel persuaded his surrogate son to bring him to the brink of death so that he could make his own reckless trip to The Empty. His risk pays off when he's able to talk to Ruby's spirit. Though he has to cut some kind of deal with her to get it, when Cas is revived, he proudly reveals that he extracted the real location of the Occultum from her -- and, what the Occultum is: "The safest place in the world."
The group heads to a white church in the middle of nowhere in the dead of night, an experience made all the creepier when -- as Dean picks the lock -- the growl of Hellhounds echoes from the surrounding woods. Inside, things take an Indiana Jones-style twist when the full moon shines through the shape of a cross in the building, leaving the pointed tip of the glowing pattern on the floorboards to point to the mysterious item's final resting place. Once unearthed, the Occultum turns out to be a golden sphere with an Enochian inscription, which Castiel translates: "In order to be in the Occultum, the Occultum must be in you."
Thinking on his feet, Jack does something that Dean would brand as "Winchester dumb," and swallows the ball whole. His whole body glows and then he suddenly flashes and disappears entirely. When he wakes up, he's inside a beautiful garden -- and you don't need to be a Biblical scholar to figure out that this can only be Eden. A young girl appears and queries his arrival in a place humans are forbidden to enter. Jack tells her that he was told this place would change him. "Perhaps," she replies. "If you were the one meant to find it. You'll know soon enough." Her exit prompts the appearance of a yellow snake with a deep, devilish voice that probes Jack's identity, forcing him to experience a series of flashbacks to his past good and bad deeds.
Back in the church, the Hellhounds finally overwhelm Sam -- who had been holding the doors shut -- but Jack returns from Eden in the nick of time, encased in a holy light so bright that it illuminates and blasts away the invisible beasts. At the bunker, Cas reveals to a worried Sam and Dean that Jack's trip to the "crossroads between humanity and divinity" did indeed change him. With the restoration of Jack's missing soul comes the resurrection of his human empathy, and the Winchesters are left speechless as the tearful Nephilim begs for their forgiveness for what he did to Mary.
Airing Mondays at 8 p.m. ET/PT on The CW, the final season of Supernatural stars Jensen Ackles, Jared Padalecki, Misha Collins and Alexander Calvert.