Handle on array setted to Backbone collection

Folks, how I could 'catch' event when Backbone collection receives array with data? I need this to loop data and join some items on some conditions. I have:

MyColl = Backbone.Collection.extend({
    model : App.Models.Movie,
    url: '/movies/start',
    events : {
        'then': 'show', // no one is calling
        'fetch': 'show'
    },
    show: function() {
        console.log(this.models);
        console.log(this.collection);
    }
});

And after fetching, when data is coming to collection, I need to do some magic stuff with data. Thanks for your answers.