Crowley manages to locate the demon tablet. He forces a kidnapped Kevin Tran to translate it for him. Kevin learns much from it, but uses the knowledge to trick Crowley and kill the demon guards watching over him.
Now free, Kevin runs away with the tablet. He hides it in a presumably safe location, and uses the knowledge he gained to defend himself from other demons. Upon being reunited with Sam and Dean Winchester, Kevin attempts to retrieve the tablet from its hiding place, only to discover that Beau has taken it.
In order to retrieve the tablet, Sam, Dean, Kevin and Kevin's mother Linda accept an invitation to Plutus' Auction House, where they must purchased it. Crowley also joins the four in hopes of beating them to it. The angel Samandriel, determined to fulfill his duty of protecting the Word of God, also joins in.
Ultimately, Linda wins the bid by selling her soul for both the tablet and Kevin. Crowley responds by possessing Linda and running away with it. He succeeds in only taking the tablet, while Linda is left in a catatonic state.
Without Kevin, Crowley turns his attention towards future prophets in hopes one of them can translate the tablet's contents. None of them are able to read it, however, Delta Mendota rattles out Kevin's location to Crowley and the current prophet is brought to the warehouse. Crowley tortures Kevin and kills one of the future prophets in order to compel him to various titles.
Kevin does, but before he can reveal too much, Castiel arrives and breaks the tablet in half, allowing Crowley to escape with only one half of the tablet.
Kevin continues to try to translate the half of the tablet in his possession, albeit to no avail. This sends Sam, Dean and Castiel on a hunt for Crowley's half. After weeks of non-stop work, Kevin finally manages to translate the section of the demon tablet on how to close the gates of Hell. According to Kevin, the person closing the gates must do three trials and recite an Enochian spell after each trial. From his half, Kevin is only able to decipher the first trial.
In the end, it's Sam who does the trials by being the one to kill Crowley's hellhound and bathe in its blood, as per the first trial's requirements. Kevin then deciphers the second trial, revealing Sam must rescue an innocent soul from Hell and release it into Heaven: said soul turns out to be Bobby Singer. Due to growing paranoia, Kevin ends up hiding his half of the tablet in case Crowley finds it. Crowley himself notes Kevin got the good half while he possesses the useless information.
Crowley does capture Kevin again, leaving Sam and Dean with no clues on the third trial, but Crowley without the tablet as Kevin hid it.
Under Crowley's supervision, Kevin translates Crowley's half of the demon tablet, but secretly sends messages to Sam and Dean. Kevin's messages lead Sam and Dean to the Scribe of God, Metatron. It is Metatron who rescues Kevin from Crowley's clutches, bringing Crowley's half of the tablet with Kevin. Using Crowley's half, Kevin is finally able to decipher the third trial: cure a demon.
In order to do this, Sam and Dean meet up with Crowley pretending to trade the demon tablet for the Angel Tablet which Crowley now holds. The whole meeting is a ruse meant to allow Sam and Dean to capture Crowley for the ritual.
The demon tablet, now whole, remains with Kevin until Metatron, a proven traitor, sends Gadreel to steal the tablets. Gadreel manages to enter the Men of Letters bunker using Sam as a vessel. He kills Kevin and takes both the demon and angel tablets. Gadreel later delivers them to Metatron.
The demon tablet eventually goes missing. Castiel had hoped to use it to find a way to remove the Mark of Cain from Dean's arm. Castiel finds out from Metatron later on that the Mark is not mentioned on any of the tablets.
It is later revealed that the demon tablet was hidden in a library. The only clue to its location is a quote from Metatron's favorite book. It is hidden in the same library as Castiel's remaining grace. While Castiel retrieves his grace, Metatron runs off with the tablet.
Metatron's last known hiding place for the demon tablet is under his mattress inside his apartment. He claimed it was impossible for anyone to find it, but Castiel proved otherwise.
The Demon tablet contains information on how to repel and kill a demon, such as a spell that can obliterate demons, a demon's weakness to Holy water, how to make a Devil's Trap and ingredients for a demon bomb.
The tablet contains info on the Trials of Hell, which will seal the gates of Hell forever and banish all the demons. "The person closing the gates must do three trials and recite an Enochian spell after each trial. Whosoever chooses to undertake these tasks should fear not danger nor death nor getting your spine ripped out through your mouth for all eternity."
The first trial demands the person to kill a hellhound and bathe in its blood. The second trial demands the person to rescue an innocent soul from Hell and send it to Heaven. The third trial demands the person to cure a demon. Afterwards, the spell is complete and the caster dies as a sacrifice.