Harry Potter and the Beast(s) and Draco

When Draco goes missing on an Auror operation and they don't want to spare the resources to look for him, Narcissa hauls Harry out of his depression to find her son. The decrepit Greengrass Manor conceals far more than Draco's fate, though, and the old enemies become unexpected allies in a fight against the Ministry, Death Eaters, and a dead man's hatred.