From A Wiki of Ice and Fire
Acorn Hall is the seat of House Smallwood. Arya Stark and the Brotherhood Without Banners stop here in their search for Lord Beric Dondarrion.
Acorn Hall has stone curtain walls and a large oak keep. The keep had a forge which hadn't been used for a considerable amount of time.
A Storm of Swords
During the War of the Five Kings, Lord Smallwood is away fighting for his liege lord and in his absense, the gates of the keep were closed and barred and few men remained to hold it.
Arya Stark and the Brotherhood Without Banners including Tom Sevenstrings, who had once been Lady Smallwood's lover, travel through Acorn Hall where Lady Smallwood welcomes them, opening the keep's gates for them to rest there. Lady Ravella notices Arya's dirtiness and forces her to take a shower and clean herself, though not knowing who Arya really was. Afterwards, Lady Ravella chats with Arya discussing tastes and the courtesies of a lady after discovering that Arya was highborn.
The Brotherhood feast with Arya and Lady Smallwood on the keep's hall asking the lady if she had word of Lord Beric Dondarrion and soon everyone begins chatting with each other. Lady Smallwood mentions that the Ser Jaime Lannister had escaped Riverrun and is currently being hunt down. Earlier, some Karstark men had gone through Acorn Hall looking for Ser Jaime.
After the feast, Gendry and Arya go to the forge where they talk about Thoros of Myr and Gendry compliments Arya for her new, more highborn looks. The day afterwards, Lady Smallwood makes Arya take another bath before parting ways with the little lady and the Brotherhood Without Banners, who proceeded with their journey to find Lord Beric.
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