Megamaser disks give one-step geometric distances, no ladder, no candles, no CMB, and the Megamaser Cosmology Project finds H₀ = 73.9 +/- 3.0 km/s/Mpc (Pesce et al. 2020). Every proposed ladder systematic, Cepheid crowding, dust, supernova calibration, is irrelevant to this method, yet it lands on the SH0ES value, not Planck's 67.4. The geometric witness says the local expansion really is fast.
ΛCDM permits exactly one H₀: a constant Λ in a homogeneous FLRW background makes the expansion rate a global number, identical whether measured at z of 0.02 or inferred from z of 1100. Two clean measurements that disagree mean the model is wrong somewhere, and the megamaser result removes the option that the local one is dirty.
SCT replaces the hot-dense-center with a superluminal collision, and the constant Λ with the dynamical ratio Λ_eff(x,t) = C × Λ_parent(x,t) / λ_local(x,t) (P17). The expansion rate then carries an environmental signature: within the KBC supervoid, whose 20 percent underdensity suppresses the local binding term, Λ_eff is enhanced and the locally sampled expansion runs 4 to 7 km/s/Mpc above the global value, combining the void contribution, the temporal evolution of Λ_eff since recombination, and the frame-tree correction (P19, P18, P10).
The megamaser galaxies sit at 50 to 130 Mpc, inside the enhanced volume, so SCT predicts precisely what the MCP measures: a clean geometric method, immune to every ladder systematic, still reading high, because the enhancement is in the spacetime being measured rather than in the rungs of any ladder. The agreement between megamasers at 73.9 and the ladder at 73.0 is the signature of a physical local effect; if the tension were a ladder artifact the two methods would disagree with each other, not jointly with Planck.
This is the same environmental Λ_eff that produces the Migkas directional H₀ anisotropy and the DESI evolving dark energy preference. Both H₀ values are correct measurements of different things: Planck reads the global expansion, the masers read our neighborhood. There is no need to invoke early dark energy, extra relativistic species, or undiscovered ladder systematics.
The registered kill: environment-tagged expansion measurements finding no systematic H(z) difference between void-dominated and overdensity-dominated sightlines at the 2 percent level after peculiar-velocity corrections would falsify the environmental enhancement that explains the maser value. Sharper still: megamaser-quality geometric distances beyond the KBC volume (z above 0.1) reading 73 rather than drifting toward 67 would break the predicted radial profile of the enhancement.