Arya Stark killed Walder Frey and then impersonated him to kill his sons.
After the Deadly Feast, she pulls off her mask and tells Frey's wife,
When people ask what happened here, tell them the North remembers. Tell them Winter came for House Frey.
Then she walks out and nobody stops her.
Wouldn't the castle guards rush in to capture her? None of the handful of women standing around the feast hall rushed out to call for guards.
Wouldn't she have to get past dozens of guards? Guards at the entrance to the feast fall. Guards at the castle door. Guards at the castle walls and castle gate. Guards in the field. How could she get more than a mile without guards chasing after her?
How did she escape?