Volcano expert Chris Horsley is called back to the Congo to investigate a potentially lethal threat to over 2 million people. After a recent eruption, a huge 16-kilometre-long fracture has appeared in the ground. He races against the clock to determine the threat level, and to locate signs that disaster may be imminent.

Volcano expert Chris Horsley is called back to the Congo to investigate a potentially lethal threat to over 2 million people. After a recent eruption, a huge 16-kilometre-long fracture has appeared in the ground. He races against the clock to determine the threat level, and to locate signs that disaster may be imminent.