"Adrenaline Rush" is the 611th episode of Casualty and the 21st episode of the 22nd series. It was preceded by "Broken Homes" and followed by "Take It Back". The episode was directed by Diana Patrick and written by Stephen McAteer.
In a chocolate factory a man has fallen into a chocolate vat. Dixie jumps in to rescue him after he starts to drown, she then gets stuck and begins to sink with the patient but is rescued by the fire brigade. Meanwhile a woman's leg is amputated when a train runs over it and is brought into resus. New nurse Lewis is straight into resus but Tess quickly sends him out due to his lack of experience. Kelsey and Alice set up dating sites after Adam suggests it to them. The patient from the chocolate factory stops breathing for no reason while being treated by Lewis and is rushed into resus where Harry praises Lewis for his quick response. It turns out that the woman wanted the train to amputate her leg so Zoe diagnosed her with BIID (Body Integrity Identity Disorder, desire for elective impairment). After Maggie interferes with Zoe's patient, Zoe makes it clear to Maggie that she won't tolerate it. Her patient then begins to spasm while Lewis takes her up to theatre. Tess shares her suspicions about Lewis to Abs. While Tess is taking a patients body to the morgue she is ambushed by Lewis who injects her with the same substance he gave to the other patients. Big Mac finds her and races her into resus. The team begin to treat her and as she begins to regain consciousness she warns the team that it was Lewis and they seal off the hospital. Big Mac successfully manages to apprehend him. Lewis says that he did what he did, so that he could then save their lives in resus and impress other people. After the shift Adam goes out to an engagement party where he meets Jessica Harrison and they have a one night stand together.