A homeless lady's body is found on a building site. Haynes investigates. She died of chorine gas. The site is run by a man convicted of fly tipping a few months ago. He has let a mate dump cleansing agents down a man hole. Garfield is investigating a discharge of waste down by the river when the informant collapses. The fumes makes Garfield woozy as well. Informant died of cyanide gas poisoning. Dashwood and Lines want June to do 50 PNC checks but get diverted to the chemical tipping cases. Both cases are linked.