Adam and Dash find Tony Timms, intrepid reporter for the Mt. Thomas Gazette, dazed and injured on the riverbank while they are investigating a reported explosion. Tony is eager to recover his camera but he won't say who attacked him or why he was there - but promises his story will "rock Mt Thomas to its very foundations." Speaking of rocking foundations, Keith Purvis strolls in to the station to report the theft of his gelignite explosives. The Heelers get a clue after they attend a charity dinner at the Imperial after all of those who eat the fish come down with food poisoning. Could it be that the Mt. Thomas River is polluted? Sure enough, the Heelers discover some suspicious looking barrels in the river. But Doctor Zoe's tests show that the drum contents had nothing to do with the fish poisoning. Meanwhile, Chris reports that the Akubra hat containing the money collected at the charity dinner has gone missing. The suspects include Keith Purvis and his new lady love, local pig farmer Doris Little. Or was it Jeanie, the cook, resentful of the implication that she poisoned the fish? And how was Tony Timms and his keen youth trainee involved? Maggie and PJ realise they won't find the answers unless they can find out just why Tony was attacked. Obviously, Tony suspects someone of environmental pollution, but who? The pair find themselves turning into investigative reporters to follow his story leads. But the answers they find are not what they expected.