Hermione walked aimlessly down the streets of non-magical London. She told herself she was shoring up her mental catalogue of crossover points, those protected spaces that connected the two Londons together, but that was just an excuse. She hadn’t even cracked the spell to uncover them properly yet, although she was getting close: in its current form, the spell caused all the sewage outlets nearby to light up with a soft yellow glow, only visible to the caster. Useful to someone, to be sure, but not quite what she needed.