The Poseidon Crew track a gold-rich ancient riverbed, Jacqui and Andrew hunt in the extreme wilderness of Central Queensland, and Shane and Russell's new washplant could leave them high and dry.

The Gold Timers call in Rob's grandfather and unearth their biggest haul ever, Shane and Russell push their sluice to breaking point, and Marcus and Dale finally unearth a monster nugget.

Jake is hauling 250,000 dollars' worth of cattle, Des must deliver a massive 101 tonnes of railway ballast to Queensland, and Glenn is racing against time to deliver 70 tonnes of salt lick.

A robbery at the Gold Retrievers' camp heaps more pressure on Brad and Chris' partnership, Marcus and Linden finally hit a rich patch of nuggets, and the Goldtimers call in reinforcements.

Who'll claim the top spot on the season's tally board? It's Squizzy versus Bryce versus Myles. And it's anyone's game.

A gigantic tower crane crashes across two city blocks in Manhattan, a raging inferno threatens a historic bridge in Pennsylvania, and what triggered a catastrophic dam failure in Idaho?

Donnie gets unceremoniously terminated by mine manager Dan at the 1870 mine, and Scratchy Moo owners Matt and Damo have a new opportunity to make some quick cash.

The Dust Devils' entire operation is forced to shut down as The Poseidon Crew's dig zone floods, forcing them to abandon their deep pit mining and defend their detecting patch from rival prospectors.

The Gold Gypsies make a discovery that could catapult their season, the Victoria Diggers hit red tape - pushing Neville to the edge - and the Goldtimers confront gold thieves.

Mike and Avery visit Avery's childhood home, a Rust Valley newcomer gets help rebuilding his dream, and Mike's '68 Chevelle rises from the dead.

PJ and Andy scramble to produce big gold after their main investor gives them an ultimatum.

The Dirt Dogs' massive dry blower shuts down due to extreme 50-degree Celsius temperatures and the Mahoneys and Gold Gypsies take a last-minute gamble that delivers big gold.

Neville and Mick's final hunt of the season is set to deliver another monster nugget; Dirt Dogs' Jake secures a last-minute deal; Scrapper Alex pays the ultimate price for gambling his life savings.

In the face of harsh weather, an emergency repair threatens vital deliveries and a veteran skipper has one last chance at a big catch.

Michael and Cherie are determined to make the most of their surface claim while conditions are good, and Ray and Paul head underground in the hope of finding a green sapphire.

PJ and Andy scramble to produce big gold after their main investor gives them an ultimatum.

An armed trespasser threatens the Gold Devils' exploration mission, and the Ferals uncover the biggest gold nugget of their mining careers.

The new team of Alan and Salty take the plunge in search of underwater nuggets, and the Ferals hit a rich patch but are forced to chase away thieves.

In the United Kingdom, engineers battle tight deadlines, complex terrain and live infrastructure to build HS2 - a record-breaking high-speed railway linking London and Birmingham.

The $50,000 dryblower at the 1870 mine is generating much-needed gold, and Ritchie heads to the Gold Coast to try to sell a showpiece gold nugget for $30,000 to one of his cashed-up socialite mates.

Bill McCoy was a Prohibition-era rumrunner whose ingenuity earned him the moniker 'the real McCoy'; we also delve into the colossal counterfeit euro network that flooded Europe with fake currency.

Dale's business is growing, but so are the risks. A cliffside wreck recovery forces him to face fears and prove he's up to the challenge.

Ray takes on the job of sawing through a massive gem, Todd and Bri get a whole new appreciation for each other's jobs, and is it wishful thinking when the Bushies reckon they've finally hit payday?

The Wildcard crew heads to a risky fishing spot known for sharks, a gamble that puts their season target in jeopardy; with tensions high, pregnant Jess faces a terrifying challenge.