Scientists investigate a mysterious meteorite shower in the rural English countryside. The events attracts attention due to the way the meteorites fall - in a spectacular "V" formation. As the investigation ensues, each of the scientists is eventually taken over by an unseen alien force, while others in the area begin dying from a mysterious "crimson plague," which covers their bodies with drops of blood. Only one scientist, Dr. Richard Arden, can save them. Immune to both the alien force and the "crimson plague," Arden works tirelessly to uncover the reasons for his immunity before the true and sinister alien plan unfolds.