The Hammersley uncovers a sophisticated drug smuggling network, with explosive results. Mike is convinced the Federal Police are covering up the poisoning death of a marine biologist. Kate is jealous of Mike's relationship with Ursula Morrell, while Nikki struggles to restrain her feelings for ET.

The crew must stop beach frolicking now Toby 'Chefo' Jones plans to propose, for a mayday. It seems a pirate boat, but carries only boat refugees. Alas some splashing water contains microscopic Irukandji jellyfish, whose poisonous bite may be fatal for Chefo and John 'Jack' Jaffah. Chief petty officer Andy 'Charge' Thorpe has something irritating an eye. Petty officer Pete 'Buffer' Tomashevski gets refugee Samira to talk about the scum firing a flair at them and takes their side, unlike Robert 'RO' Dixon, who grumbles he must fill in as cook. Billy 'Spider' Webb is heartbroken when his recruitment 'class clown' Jaffah doesn't make it.