New Zealand: Writing a book, need information

I have a series set in New Zealand, and two of the characters go rock climbing. One is fearless and has climbed for years. The other is not. I want to know where they should climb. It has to be somewhere where they can reach the top in a day. I'd like it to be a little scary for her, a smooth surface at least in some areas. They will be using gear, ropes, etc. But I want it to be a scary experience for her. I want her to have to feel around nervously for a place to stick her fingers as she tries to climb this monster. Any suggestions? I appreciate any info you can give me on a specific place like how high it is and what the surface is like. Don't take it easy on her. This needs to be a climb that would scare the hell out of a beginner.

Google mount cook.

You need to be a bit more specific - what part of the (surprisingly large) country - at least which island? Single or multi-pitch. Is she just scared but ultimately capable, or is it something where the guy had no reasonable excuse for bringing her along? Real danger, or just perceived danger? Purely rock, or alpine?

If you say should be able to get to the top in a day, it kinda implies that it should take longer than ~ 30 min, and should be at least multi-pitch trad. With the idea in mind that it should be a reasonably long route, here are a handful of suggestions for areas.

Purely rock cragging, long multi-pitch, at least some trad routes, low objective danger, routes could be plenty scary and take several hrs if you were epicing, but not really negligent to take a relative beginner:
- Whanganui Bay, Castle Rock (Coromandel), Sebastopol Bluffs

Semi-alpine, rock cragging, shorter routes than above, but longer approaches, some (but relatively little) objective danger, challenging weather, not completely unreasonable for a relative beginner:
- Any of the crags on the north island volcanoes in summer

Long multi pitch alpine rock, some objective danger, very challenging weather, possibly technically OK for a beginner with an experienced guide, but absolutely not advisable.
- Grave-Talbot pass (this is mostly a hiking route, but has a few technical sections)

Long multi-pitch alpine rock, very challenging weather, criminally irresponsible to bring a beginner on.
- pretty much anything else in Fiordland / Darrans

That's left without mentioning anything which would need an ice axe, or which is essentially a scramble/hike. If you want more alpine (snow) trips, Taranaki in the North Island or around Arthurs pass in the South are places you could take a beginner to and get into a whole lot of trouble.