Sergeant Alex "Swansea" Hughes is called out at night to a woodland near Clitheroe, where a dog walker has found an explosive dating back to the Second World War. Swansea must make it safe by taking it to a large open field and blowing it up. Sergeant Sam Jones - a veteran of Afghanistan - has seen a spike in the number of calls the bomb squad receive in the UK due to the craze of magnet fishing. Treasure hunters hurl large industrial weights into lakes and canals but often get more than they bargained for, pulling out all manner of potentially deadly explosives including mortar bombs and hand grenades, with one man causing a major incident by disposing of a grenade in a dustbin on the industrial estate where he works.

Members of the Army's EOD and Search Regiment head to the Isle of Man, where police believe they have found a bomb-making factory in a garage, while Sgt David Podmore investigates when the coastguard reports a possible torpedo on a Wirral beach.