Barbara Lott, Johnny Ball, Liz Hobbs

An amusing game of logic and ingenuity broadcast from Arg, on the far side of the galaxy.
His Highness, the Rangdo of Arg, delights in testing the perspicacity of any visitors who arrive on the planet in search of the Great Crystal.
Will his problems baffle this week's trio, or will they enter the Black Mine?
The explorers this week are Johnny Ball, Barbara Lott and Liz Hobbs