Flash#176(1968)

Iris Allen lies in a hospital bed with a severe case of Grippe. Her fever spikes and she suddenly goes into a coma. While she is in her comatose state, Iris keeps murmuring Flashes name. She seems to be in a deep nightmare. Barry is beside himself with worry as to how he can help his wife. He desperately wants to wake his wife out of her nightmarish dream but feels hopeless. He then recalls a certain area in the Spectrum of Velocity where he experienced a strange haunting feeling. He decides to break the speed of light barrier to investigate the strange Velocity Spectrum. Once he finds it he enters the strange band and sees that it is filled with people experiencing nightmares. He finds Iris in the dimension and views her nightmare. Iris is standing as she views the Flash battling a figure of death itself. The Flash figures that he is going to have to defeat death in this nightmarish realm to wake his wife out of her coma. He discovers that the death figure is sensitive to light and he uses his body to vibrate at a certain speed to generate light that defeats the figure of death. He dispatches the figure as it warns him that Death will eventually win. The Flash then runs back to the hospital to find that Iris is recovering nicely.