If I try to counter a flashback spell using "Grip of Amnesia," what happens?

From what I know about magic, instant spells go on top of the stack, so "Grip of Amnesia" happens before the flashback spell is casted.



If the opponent chooses to remove his or her graveyard, it removes the flashback spell before he can play it and he mana burns?



If the opponent chooses not to remove his or her graveyard, does the spell get removed from the game because he casted it? Or is it never casted successfully and he just uses up his mana and the card stays in his graveyard? Or does nothing happen at all?



Please explainIf I try to counter a flashback spell using "Grip of Amnesia," what happens?
Technically, the flashback spell would temporarily leave the grave to go on the stack. Thus, if you were to play "Grip of Amnesia", and assuming "Grip of Amnesia" is on top of the stack on top of the flashback'd spell. 1) If your opponent removes his graveyard, his graveyard is removed THEN his flashback spell takes place THEN it is removed as it resolves, and then the rest of the stack... 2) If your opponent does not remove his graveyard, well your "Grip of Amnesia" counters his spell, but his spell has to be removed because that's part of being flashback'd.



For the record, there is no mana burn anymore.