Papa Smurf's lab explodes while he was making the formula "Ad Capitis mala et alios dolores sanandos" (which is about as far as Brainy Smurf can read because he is unable to translate the writing as he claims) and when the other Smurfs arrive, Papa Smurf is unconscious. A Smurf goes to Homnibus' home to ask for help. Homnibus discovers that Papa Smurf has fallen sick due to using sulfur in the formula, but he lacks the linden stipules needed for the antidote, so he sends Oliver to buy some. The Smurf goes with Oliver and learns about money and the humans' commerce system.