Common Vector

 was the third episode of Series 26 and the 780th episode of Casualty overall.

Plot
New mum Annie, skateboarder Richie, white-collar worker Chris and protected teenager Fiona are all admitted with sickness and dilated pupils. Observant doctor Dylan soon notices a pattern but what is the common link? With the patients deteriorating, the race is on to get to the bottom of the mystery. Could the connection be a poisoned supply of heroin which has found its way on to the streets? And will the team get to all the patients in time – including breastfed baby Evie?

Meanwhile, new nurses Lloyd and Scarlett struggle with the emotional demands of their jobs and Linda finds her attitude softening towards young drug addicts Annie and Chloe.