When the Boat Comes In - Season 4 Episode 4 Flies & Spiders

Smuggler Doughty introduces Jack to his supplier, German Captain Bauer, who offers Jack work guarding an air-strip in South America against local tribes. However, on learning that Bauer wants the locals killed for the oil on their land, Jack refuses. Nonetheless, he buys a warehouse full of fire-damaged, bankrupt goods from Bauer, which he and Sarah sell in Gallowshield market. Jack's able to repay Matt's debt and retain a handsome profit, though he's less fortunate in love when Margaret, for whom he has fallen, returns to London to get married.