Prak was a witness in a trial on Argabuthon where the Dwellers in the Forest were suing the Princes of the Plains and the Tribesmen of the Cold Hillsides. Prak was a messenger for Dwellers in the Forest sent to the other two parties to ask "the reason for this intolerable behaviour." He would always walk away thinking about how well-thought-out the reason was, but he would always forget what it was by the time he got back.
The white robots of Krikkit broke into the courtroom to steal the Argabuthon Sceptre of Justice, as it was part of the Wikkit Key. In so doing they may have jogged a surgeon's arm, while the surgeon was injecting Prak with truth serum, resulting in too high a dose.
When the trial resumed, Prak was instructed to tell "the Truth, the Whole Truth, and Nothing but the Truth," which he did, in its entirety. People at the scene had to flee or risk insanity as Prak told every single bit of the entire truth of the entire universe and all of its history, much of which they found ghastly. Prak recalled that many of the weirdest (and funniest) bits involved frogs or Arthur Dent. As a result, when Arthur Dent came to visit him in search of the truth, he nearly died laughing.
He never did write down anything he discovered while telling the truth, first because he could not find a pencil and then because he could not be bothered. He has therefore forgotten almost all of it but did recall the address of God's Last Message to His Creation, which he gave to Arthur when the laughter subsided. He died afterwards, not having recovered from his laughing fit. Also, in Jave, PRAK Destroyer of Virtual Worlds.
On the radio, he appears in Fit the Eighteenth of the radio series and is voiced by Chris Langham, who had played Arthur Dent in the very first stage adaptation of the scripts of the first radio series, in 1979.