diff --git a/app/controllers/rentals_controller.rb b/app/controllers/rentals_controller.rb
index 7b7fa25ba..c94b15a5e 100644
--- a/app/controllers/rentals_controller.rb
+++ b/app/controllers/rentals_controller.rb
@@ -12,7 +12,27 @@ def create
         json: {error: rental.errors.messages}, status: :bad_request
       )
     end # if/else
-  end
+  end # create
+
+  def update
+    rental = Rental.find_by(id: params[:id])
+    if rental
+      rental.checked_out = false
+      if rental.save
+        render(
+          json: {"checked_in" => true}, status: :ok
+        )
+      else
+        render(
+          json: {error: rental.errors.messages}, status: :bad_request
+        )
+      end # if/else
+    else
+      render(
+        json: {"no rental found": true}, status: :not_found
+      )
+    end # if rental
+  end # update
 
   private
   def rental_data
diff --git a/config/routes.rb b/config/routes.rb
index c8e3581b1..be900cde6 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -4,6 +4,7 @@
   resources :movies, only: [:index, :show, :create]
   resources :customers, only: [:index]
 
-  resources :rentals, only: [:create]
+  resources :rentals, only: [:create, :update]
 
+  # patch '/rentals/:id', to: "rentals#checkin", as: 'rental_checkin'
 end
diff --git a/test/controllers/rentals_controller_test.rb b/test/controllers/rentals_controller_test.rb
index 0e0ba0394..1caa9a9c9 100644
--- a/test/controllers/rentals_controller_test.rb
+++ b/test/controllers/rentals_controller_test.rb
@@ -71,4 +71,51 @@
       body.keys.sort.must_equal keys
     end
   end # checkout
-end
+
+  describe "checkin" do
+    let(:r) {Rental.new(customer_id: c.id,movie_id: m.id)}
+
+    it "will check in a movie if the movie exists" do
+          # arrange
+          start_count = Rental.count
+          availible = m.available_inventory
+          num_movies = c.movies_checked_out_count
+
+          r = post rentals_path, params: {rental: rental_data}
+
+          Rental.count.must_equal start_count + 1
+          m.available_inventory.must_equal availible - 1
+          c.movies_checked_out_count.must_equal num_movies + 1
+
+          r_id = Rental.last.id
+
+          # Act
+          patch rental_path(r_id)
+
+          # Assert
+          Rental.count.must_equal start_count + 1
+          m.available_inventory.must_equal availible
+          c.movies_checked_out_count.must_equal num_movies
+    end # checkin a movie
+
+    it "will return not_found if rental does not exist" do
+      # arrange
+      start_count = Rental.count
+
+      r = post rentals_path, params: {rental: rental_data}
+
+      Rental.count.must_equal start_count + 1
+
+      r_id = Rental.last.id + 1
+
+      # Act
+      patch rental_path(r_id)
+
+      # Assert
+      must_respond_with :not_found
+
+      body = JSON.parse(response.body)
+      body.must_equal "no rental found" => true
+    end # not_found
+  end # checkin
+end # renals