Which aguile du midi ticket

Hi, I'm very confused by the aiguille to midi ticketing.

I'm hoping to walk up to the Plan, then get a return ticket to the aiguille du midi, then walk back down from Plan.

Does anyone know what ticket I need? I see the "Ticket round trip plan de l'aiguille" but it's not obvious if this is chamonix-plan-chamonix or plan-aiguille-plan.

Thanks!!