An illegal arms racket is discovered after a suspicious container at Tilbury Docks explodes, almost killing Barry. A new elite squad known as Indigo has been formed and Barry is invited to join. Alex is frustrated at being passed over.
Brother and sister Rick and Jenny Foster are supplying deadly Ecstasy tablets in the clubs of Ibiza. The pair are so hard to catch that the Indigo team suspect there is a mole tipping them off.
A poisonous toad smuggling operation causes a series of deaths to Indigo team. An international drugs baron has an old score to settle with team leader Glen.
A teenager girl goes missing, an internet pedophile ring are the chief suspects. An explosion kills the main suspect. The team race to find the girl before she is killed.