An older rescue dog with only one tooth, Mason's shelter puts him on sale one day trying to help him find his forever home. When Amanda submits an application to adopt Mason, she has no idea she's mothering a cuddly boy who secretly moonlights as a fearsome, crime-fighting hero known as "The Tooth." When someone new enters Mason and Amanda's lives and changes them forever, Mason confronts a past that haunts him, a livelihood that drives him and a question he's been avoiding for years: Can he ever forgive himself?