Dr Nick Beeching examines a twenty year-old windsurfer who suspects a spider has laid eggs in the infected wound on his back. Dr Beeching also investigates a patient whose foot has been attacked by a flesh-eating super bug that’s been treated with larval therapy. Dr David Lalloo treats a woman who has been the unknowing host to parasitic worms for the past fifteen years. In Africa, he meets a young boy who’s been hit by an invasion of the same parasites which have been laying hundreds of eggs in his bladder.

Dr David Lalloo diagnoses a returning traveller with a suspected scorpion sting. This episode also follows the work of Dr Lalloo in Africa and confronts a parasitic infection which causes abnormal swelling to the victims’ legs. Dr Bertie Squire investigates another parasite which is lurking in the gut of a young woman. The parasite proves resistant to treatment. A woman returns from a holiday on Madeira and is struck down with a knock-out fever with a challenging prognosis.

Dr Helen Winslow treats a charity fundraiser who visited West Africa with a maggot infestation. In Tanzania Dr David Lalloo is on the frontline of the global fight against malaria. Dr Tim O’ Dempsey treats a holiday maker who has returned from Tunisia with a mystery lesion that won’t heal and treats a medical student who thinks he’s picked up a parasitic worm invasion after going for an ill-advised swim. Major Tom Fletcher is called to the emergency department to help a patient with breathing difficulties following a trip to the Caribbean.

Dr David Lalloo tracks venomous snakes in Sri Lanka, and observes the deadly effects their bites have on unsuspecting victims. Dr Bertie Squire investigates an unsolved mystery illness spreading through a patient’s lung. Major Tom Fletcher is challenged to diagnose a sick traveller with a unrecognisable bug. A junior doctor new to the Unit is confronted with the disfiguring Leishmaniasis parasite and in search of a cure, the patient must go through a gruelling treatment.

Dr Tim O’Dempsey treats a returning traveller, from the jungle in Peru and returned with eight maggots in her ear. Snake bite expert, David Lalloo, is confronted by a patient from Warrington who’s been bitten by his pet, a highly venomous, Samar Cobra. Dr Bertie Squire is forced to put the Tropical and Infectious Disease Unit in Liverpool on high alert, fearing a patient has returned home with one of the world’s most virulent killers. Doctors fear a young boy may have a parasitic invasion caused by the bite of the Tsetse Fly. A woman, who definitely has this condition, undergoes treatment.