In an attempt to shatter two world records, an electric-powered Land Cruiser will attempt to cross a 7km section of Darwin's harbour floor.

As Luke and Taylor prepare for the underwater drive, they dive into the mysteries lurking beneath Darwin Harbour where the world record will take place. Negotiating explosive ornaments, shipwrecks, and gas pipes, they must meticulously plan the perfect route for their 1978 Land Cruiser, now dubbed the Mudcrab. Simultaneously, challenges arise in refurbishing the Mudcrab's chassis and contemplating an electrifying transformation. The clock is ticking as the team faces unexpected twists, leading to a riveting off-road showdown against Land Cruiser experts Graham and Laurie Smith.

With the world record attempt just around the corner, Luke and Taylor confront intricate challenges, from ensuring air supply for underwater divers to waterproofing the Mudcrab's crucial components. The countdown intensifies, and the team faces a potential explosive catastrophe if waterproofing fails. Amidst the pressure, Luke seeks out top-quality rims, leading to a unique challenge at Rohmy. The team grapples with weight distribution and encounters Outback Ringers legend Kurt Hammer in a thrilling bull-catching adventure.

In Darwin, the team races against time to complete the waterproofing of the Mudcrab. With just seven days left, they work tirelessly on the fully electric vehicle, conducting underwater tests to gather vital data. The Mudcrab faces challenges such as an underwater dunk test and shoreline driving to ensure feasibility. As the team prepares for the world record attempt, an unexpected obstacle arises: they are prohibited from crossing two underwater gas pipes. In a nail-biting finale, Luke and Taylor take on the 7km underwater drive and continue Tim Proctor's 40 year old legacy.