Time is the cruelest of the gods... Aaricia has made her last breath, with white hair. At the twilight of her life, crushed by pain, Thorgal is offered the ring of Ouroboros by the perfid Nidhogg. Let him put it on his finger, and he can return to his own past, and see his beloved again. No matter the price to pay, there are temptations to which even the purest hero cannot resist...