How to create a custom Serializer for Ember data

I have an API that returns JSON that is not properly formatted for Ember's consumption. Instead of this (what ember is expecting):

{ events: [
    { id: 1, title: "Event 1", description: "Learn Ember" },
    { id: 2, title: "Event 2", description: "Learn Ember 2" }
]}

I get:

{ events: [
    { event: { id: 1, "Event 1", description: "Learn Ember" }},
    { event: { id: 2, "Event 2", description: "Learn Ember 2" }}
]}

So if I understood correctly, I need to create a custom Serializer to modify the JSON.

var store = DS.Store.create({
    adapter: DS.RESTAdapter.create({
        serializer: DS.Serializer.create({
            // which hook should I override??
        })
    })
});

I've read the code comment related to the DS.Serializer, but I can't understand how to achieve what I want...

How can I do it?

ps: My goal is to make App.Event.find() work. Currently, I get Uncaught Error: assertion failed: Your server returned a hash with the key 0 but you have no mapping for it. That's why I need to fix the JSON received.

edit: Here's how I made it work, for now:

extractMany: function(loader, json, type, records) {
    var root = this.rootForType(type),
    roots = this.pluralize(root);

    json = reformatJSON(root, roots, json);
    this._super(loader, json, type, records);
  }