Al wakes up with Jas is his bed with no idea how she got there. He’s delighted when she says he was amazing last night, but is left uneasy by Jas’s evasive response when he tells her he’s in love with her. On the way to work they meet a homeless man, Edgar Pugsley, who says he blacked out and fell. Jas thinks it may be epilepsy, but an uncaring Al reckons it’s just the booze. Edgar privately tells Al he’s ill because he drank the water at the hydrochemical plant where he used to be a caretaker, before they threatened him to keep his mouth shut and fired him.
While Edgar’s being tested at St Phil’s, Al does some investigating and visits Teresa Harrington, the wife of a patient who died after presenting the same symptoms. Teresa tells Al the company paid for her husband to go travelling and gave her money on the condition she sign a confidentiality agreement. Then she found out she was ill too, confirming to Al there was a leak into the water supply. She pleads with Al to do what she can’t and expose the company. He takes up the challenge.
Al breaks into the factory and discovers a suspicious and badly repaired pipe. He takes a swab and a picture – he’s got them – only to be nabbed by a security guard. He’s brought in front of Jacqueline Frost, the managing director. She destroys the evidence and tries to get Al to sign a confidentiality contract, but Al uses a contaminated sample to make his escape. He makes it to his car, where he reveals a phone strapped to his leg – he’s recorded her whole confession – before calling the police.
As the police take Frost away, Al returns to The Mill to a hero’s reception. He’s sure it won’t make a difference to Jas but, to his surprise, she’s won over: she loves him. All Al’s dreams come true as she drags him into the store cupboard for his hero’s reward… only for the sound of the radio to rouse Al, who finds himself alone in his bed. A dejected Al realises it was all just a dream.