When the news breaks he drinks a calming draught and goes to the Ministry and is mildly distraught along with everyone else and gets his grandfather alone and explains, piece by piece, what must have happened. " - so we could declare ourselves at war with Elio's organization but we still don't know how the spell works and she'd probably deploy it again if things escalated to an open war, I'd much sooner just assassinate her and then explain ourselves after the fact."
His grandfather did not take a calming draught, and is openly weeping. He takes a minute to consider. "I want her in Azkaban."
"Instead of dead?"
"She might know - they might not be gone -"
"They might not be gone," Fredrick says with potion-aided mild hope. "But why would she tell us? For a lighter sentence? We can't offer her a lighter sentence, thousands of people are already dead."
"The Muggles who were in the way of the sudden tampering in France."
His grandfather makes a face at him as if to say 'you think the fate of French Muggles will move me when my favorite son and five of my grandsons and all of my great-grandchildren are dead?'
Fredrick sighs. "If it's feasible to take her alive we can question her and then figure out where to go from there."
"You mean to duel her?"
"No. I'd lose. I mean to track her down via Elio's organization while they're off-balance and on the run and I mean to kill her unless I have an opening to take her alive. Father agrees with me here."
"Very well. What do you need?"
Felix is very emphatic about the invisibility cloak being well-secured and about the backup wand. Felix points him to Lisbon. He walks the streets and conveniently no one bumps into him and Felix thinks he should turn left here -