Run the staircase (6- 5 4 3⁷), then take the deep route: the home key's ♭7 major — rock's favorite borrowed chord — is ALSO the Neapolitan of the 6-, and aimed at the 3⁷♭9 it stops being rock and becomes flamenco. Same chord, two passports. The full cell — 2- → ♭7 → 3⁷♭9 → 6- — is the Phrygian cadence with its papers in order.