The shackles of our Free Will

While cleaning his old desk at the beginning of his return to Grimmauld Place, Sirius discovers some old Postcards that remind him of a potential alley for the war against Voldemort in Mainland Europe. But this alley isn't what she was all those years ago and Sirius has to make a choice: help Harry at great cost to himself or put his trust in Dumbledore's plan.