Two years have passed since the vampires, led by the Master, used atomic weapons to create a nuclear winter, blocking the sun almost continuously and allowing the vampires to move freely, except for 2--3 hours when sunlight filters through.
Two years have passed, blocking the sun almost continuously and allowing the vampires to move freely. This was except for 2--3 hours when sunlight filters through. The vampires used atomic weapons. This was to create a nuclear winter. The vampires were led by the Master.