Gather all ingredients.

Preheat the oven to 350 degrees F (175 degrees C).

Remove and discard giblets.

Rinse turkey and pat dry.

Season turkey with salt and pepper.

Sprinkle the bottom of the turkey bag with flour.

Place turkey in the bag and add celery and onions.

Seal the bag and transfer into a roasting pan; poke several holes in the bag with a fork.

Bake in the preheated oven until turkey is cooked and the juices run clear, about 3 to 3 1/2 hours. An instant-read thermometer inserted into the thigh meat should read 180 degrees F (85 degrees C).

Enjoy!