Horizon Zero Dawn's The Heart of Nora follows on from the events of the previous quest, Deep Secrets of the Earth, your old tribe, the Nora, is under threat.
As it turns out, it's a pretty serious threat, too. Fast travel to the Nora homeland is restricted, and on arrival you'll find your homeland torn apart by battle.
If you're after help for other parts of the game, consult our complete Horizon Zero Dawn walkthrough and guide.
The Heart of Nora
Steel yourself for some tricky battles ahead - but also note that, after all this time, you're also heading back to the location that was, potentially, the place of your birth. Here's our walkthrough for what's ahead:
Go to All-Mother - You can't fast travel directly to All-Mother, instead you need to walk the final few hundred steps, so travel to a near-ish campfire and save up there before progressing onwards. There are a number of tough enemies in the way here, but you don't have to fight all of them - the Deathbringer, for example, can be completely bypassed with some simple sneaking, which is probably worth doing.
How to defeat the Thunderjaw
When you finally reach All-Mother, a huge, corrupted Thunderjaw is laying siege to your friends, who are holed up inside the mountain. It's up to you to take it out, but some of the Nora will charge to your side once you attack it.
Use your Journal to analyse its weaknesses: Fire for the Blaze Cannister that's hard to reach on its back, and so on. We recommend shooting off the Disc Launcher with Tear damage from your bow, then using that weapon against the Thunderjaw for some significant damage.
Talk to Varl - With that taken down, talk to your old pal Varl by the mountain entrance.
Talk to Teersa - Next up, talk to Teersa, who seems understandably glad to see you.
Find the facility Control Room
Search the Ruins beyond the Hatch - It's time, at last, to go beyond that hatch inside the mountain. Follow your waypoint and search the various nooks and crannies along the way.
Search the facility Control Room - Eventually you'll reach a control room up a short flight of stairs, which houses a holographic datapoint. Watch the hologram for some story info.
For more Horizon guides, explainers and advice, take a look at our main Horizon Zero Dawn guide and walkthrough hub, or our advice on finding Horizon Zero Dawn's override Cauldrons for controlling any machine, and unlocking some super-strong armour with our Horizon Zero Dawn Power Cell locations guide, too.
Exit the Facility - Info learned, it's time to leave. Climb up the nearby escape route and back out to the tribe.
After the tribespeople have finished lavishing you with praise, it's on to the next mission of your main quest, over at the Bitter Climb, in The Mountain that Fell.