The rules concerning "The Arcane Ritual" (10.1) say :
"After the true source of the invasion has been discovered, all 3 heroes must move to that area"
What happens if one or two heroes (except the professor) are already deads when we found the source ?
Can we still try the arcane ritual or this option of victory is no more available ?
As far as I understand it, that option is no longer available.