There are amazingly detailed maps the Ecrins Nord, as there are of all the French Alps. Buy them in La Grave, Grenoble or in any big city in France. You can also study them in the  Maison du Montagne in Grenoble just a block away from the tourist office which can provide all the info you will ever need.

There are at least two very good guide books for the area. The first is L’Alpe d’huez, Les 2 alpes, La Grave hors piste by Francis Ginet and Fabrile Villaret (Vamos 1995) which is a guide to the ski hill accessed backcountry in the area. Over 100 routes in French and English, along with black and white photos of the descents. A great companion for getting to know the possibilities. The second book is the definitive guide for the ski-tourer to the area called Ecrin Nord by Shahshahani which has great descriptions of most of the tours in the Ecrin Nord area. It is available in Grenoble and La Grave and is a must if you are not planning to hire a guide. Unfortunately it is only in French.