Title: The Complete Theory: One Field, One Equation, Everything Author: Alexander Novickis (alex.novickis@gmail.com) We present the capstone of a sixty-five-paper programme: a single Lagrangian on a single manifold that produces all known fundamental physics. The Lagrangian is the Faddeev-Niemi action on $M_4 \times S^3$, $$\mathcal{L} = \frac{\kappa_2}{2}|\partial_\mu \mathbf{n}|^2 + \frac{\kappa_4}{4}|F_{\mu\nu}|^2$$ where $\mathbf{n}: M_4 \times S^3 \to S^2$ is the Hopf field and $F_{\mu\nu} = \mathbf{n} \cdot (\partial_\mu \mathbf{n} \times \partial_\nu \mathbf{n})$ its Berry curvature. This two-term action, derived from 7D Einstein-Gauss-Bonnet gravity [Paper X], admits topological solitons (knots, $H \neq 0$) identified with all matter and propagating waves ($H = 0$) identified with all radiation. From this equation alone: the electron and all charged leptons (Hopf charge $H = 1$, three generations from Casimir uniqueness $\delta = 2/9$), all six quark masses ($m_q = m_e \cdot \alpha^{-n_q/17}$, 0.1--10%, Paper LXV), the fine structure constant ($1/\alpha = 137.09$, 0.04%), the Weinberg angle ($\sin^2\theta_W = 3/13$, 0.19%), the Higgs mass ($m_H = 125.82$ GeV, 0.46%), the complete neutrino mixing matrix (all four PMNS parameters including $\delta_\text{CP}$ within $1\sigma$), the Cabibbo angle ($13.08°$, 0.35%), $|V_{cb}| = 1/24$ (1.1%), the cosmological constant (1.4%), baryogenesis, dark matter, dark energy, gravity, entanglement, spin, statistics, and the arrow of time. We present the complete derivation chain from Lagrangian to observable, compare with the Standard Model's 19+ free parameters, assess open problems honestly, and reflect on the ontological and philosophical implications of a universe made of one field. Keywords: physics, topology, soliton, unified, capstone, everything DOI: 10.5281/zenodo.19442511 Series: Paper LXIII in the Hopf Soliton Programme