Get ActiveRecord :id via has_many through

I'm trying to generate a report of products in a warehouse, through the tag number, but I need to grab the list in such a manner (likely eager loaded which...is another story):

rfid_tags = Warehouse.includes(tags: :ancestor_product).find(the_id).tags 

My associations are laid out as such:

#warehouses.rb
has_many :tags, as: :location
has_many :products, through: :tags, source: :ancestor_product

#schema - off :tag table:
...
add_index "tags", ["ancestor_product_id"], name: "index_tags_on_ancestor_product_id", using: :btree 
#foreign key for products and tags

I'm able to search for @products = Tag.joins(:ancestor_product) in the console, but I'm hitting a roadblock when trying to go further in that manner. What's missing here? I'm using Rails 4.2.