Just Because You're Paranoid

 was the thirtieth episode of [Series] and the 761st episode of Casualty overall.

Plot
Ruth is reluctant to accept her bipolar diagnosis, particularly as she feels she can't continue to be a doctor if she is constantly dosed up on lithium. But when her old mentor, Sarah Evans, arrives on the Pysch ward, Ruth is aghast, and then astonished, to learn that Sarah is actually a patient too. Sneaking out, the two go for a coffee and Sarah confides that she has OCD and is still a functioning doctor – maybe there is hope for Ruth after all. The meeting turns sour when Ruth realises Sarah didn't sneak her out at all – Charlie engineered the whole thing...

Zoe and the gang gossip about Holby's latest doctor, Dylan Keogh, and Zoe is horrified to learn that Dylan was standing behind her all along. Throughout the day, Dylan rubs most of them up the wrong way with his brazen disregard for the rules, coupled with his know-it-all attitude. Zoe softens a little, though, when Dylan persists with a treatment, which he feels is the best thing for his patient, despite being threatened with a lawsuit.

Meanwhile, after hearing about the deterioration of a former patient, the badly disfigured Hannah Fleet, Dylan reaches for, and then rejects, a glass of wine. Is he more caring than he lets on after all?

Sally Bridges thinks the world is out to get her and she is admitted to the Pysch ward after attacking fellow researchers at her university. Her mum, Donna, arrives and tells Charlie that she is working on climate change and a lot of blue chip companies stand to lose out. But when Donna goes to collect some of Sally's research, she sees her daughter's paranoid ramblings and realises that she may have mental health issues after all.

Still fuming from Charlie's betrayal, Ruth finds Sally collapsed in the toilet and, all alone, is forced to examine her. In a moment of diagnostic brilliance, she works out that Sally's symptoms could be attributed to Lymes disease. In that moment, Ruth realises that she can be a doctor again...