I'm traveling from Lourdes to Paris in mid-July. Is there alot of theft on that route? And should I be looking forward to the cabins being jam packed?
If you book a bunk in either a 4-person or 6-person couchette, your only concern would be the possibility of theft by someone sharing the couchette with you. All couchette doors lock from the inside. I recommend that you remove any valuables from your luggage and sleep with them. If you book a reclining seat, use a cable lock to secure your luggage to a rack.
I think the second class couchettes on those French Intercites night trains are 6 bunk. As Tim says, they have locking doors. Full details and photos on the wonderful Man in Seat 61 website, here: http://www.seat61.com/lunea.htm#.UahupUDFX6Y