After a meeting in the Professor's office they left with more questions then when they had walked in.  The three were informed of such a thing as a "Horcrux" and that Tom Riddle had harnessed this power and had created them to become more powerful with intent to survive his first downfall. They had to find these Horcruxes and destroy them as best they could. After arguing, fighting and bashing heads, they agreed and had mutually decided that they were going to find these Horcruxes. they were going to have to destroy these objects if they wanted any chance to defeat the Dark Lord.