|“||The Occultum is divine in its origin. It was housed for hundreds of years in an ancient temple before it was... (…) Looted by invading Mongol hordes for trade on the black market. (…) Until a few years ago, it was owned by the Jacobson family, until Hyram Jacobson's son fell gravely ill. And he was told nothing could be done. And in desperation, he turned to a faith healer. She saved the child, but she would only accept the Occultum in payment.||”|
|“||It's a passage in Enochian. It says, um, loosely translated "in order to be in the Occultum, the Occultum must be in you."||”|
At some point after humanity is exiled from the Garden of Eden, God creates the Occultum to transport non-humans to the Garden. Originally stored in an ancient temple, it is looted by Mongol hordes for trade on the black market. It eventually winds up in the hands of the Jacobson family, but Hyram Jacobson's son falls gravely ill. Taking the boy to the angel Anael, Hyram trades the Occultum for Anael healing his son.
After receiving the Occultum, Anael contacts the demon Ruby and suggests that they use the Occultum, the safest place in existence, to hide out until the Apocalypse is over. Ruby hides the Occultum in an abandoned church guarded by two hellhounds. However, Ruby doesn't tell Anael where to find the artifact, knowing she can't be trusted and is killed by Dean before the two can set their plan into motion.
In Destiny's Child, Billie informs Jack that his next quest to become strong enough to kill God is more spiritual in nature: find and use the Occultum. However, Billie refuses to explain what the Occultum will do for the young Nephilim and doesn't know where it can be found as the Occultum is hidden beyond even Billie's ability to locate it.
Searching through the lore for clues, Sam finds barely even a mention of it and nothing on where it can be found. In desperation, Castiel contacts the shaman Sergei who helps him trace the history of the Occultum from its theft to the faith healer Hyram Jacobson traded the artifact to. Though Sergei is unable to provide a name for the faith healer, the Winchesters and Castiel, having had experience with Anael, recognize the angel. Confronted by the Winchesters, Anael fabricates a tale where Ruby approached her and offered to sell the Occultum for millions of dollars on the black market. Anael claims that Ruby hid the Occultum in Hell before Dean killed her, but this is a trap and Anael attempts without success to have the Winchesters killed by three demons rather than give up the artifact.
Suspicious of Anael's story, Castiel has Jack drain most of his life force so that he can enter the Empty and ask Ruby herself about where to find the Occultum. Ruby points out how obvious it is for a demon to hide something in Hell and explains the true story behind her deal with Anael over the Occultum. Castiel is surprised to learn that the Occultum is a place, but Ruby tells him that "a place, a thing, whatever you want to call it, its powerful" and she cut a deal with Anael and stashed the artifact. Ruby states she can tell Castiel where to look and that its not in Hell. Ruby assures the Seraphim that Anael doesn't know as Ruby didn't trust her with the secret and asks for Castiel to promise to at least try to get Ruby out of the Empty in return. Ruby whispers the location of the Occultum in Castiel's ear before vanishing.
After being brought back to Earth by Jack, Castiel reveals his success at finding the Occultum, the safest place in the world which Anael would never be willing to give up. After setting up an alternate Sam and Dean to trick God if he comes to check on them, the Winchesters, Castiel and Jack travel to the church Ruby indicated, only to find it guarded by two hellhounds that she neglected to tell Castiel about.
Taking cover in the church, the group searches for the Occultum which Ruby had told Castiel could found because the top of the cross will point the way. As they try to decipher the clue, the full moon shines through the cross-shaped window, illuminating the floor and pointing to where the Occultum is hidden beneath the floorboards. Confused by the small orb recovered from a bag beneath the floorboards, Dean and Castiel argue about the whether or not Ruby was telling the truth while Jack decides to swallow the Occultum to their shock. Suddenly doubling over in pain, Jack is transported to the Garden of Eden in a flash of light. After meeting a mysterious young girl and the snake, Jack flashes back on his life and begins crying before the Occultum transports Jack back to the church, disintegrating the hellhounds in the process.
In the aftermath of Jack's return, its revealed that his trip through the Occultum to the Garden of Eden restored Jack's lost soul.