In this season the 2009 Mount Redoubt eruptive activity caused complications; the truckers had to carry many loads which were intended for flight, but the planes could not fly because of volcanic ash in the air.
Hugh Rowland and Alex Debogorski take part in this season as newcomers to the Dalton Highway in Alaska, working alongside the following local drivers at Carlile Transportation.
Passing a spun-out truck, he nearly suffers the same fate; a recent avalanche and sudden whiteout close the road for some time, but he does meet his delivery deadline.
Thirty-year veteran George Spears and rookie Tim Freeman, Jr. set out together for Prudhoe Bay, hauling steel housing panels and canned food, respectively.
In Fairbanks, Lisa picks up a set of truck tires (her first oversize load) and finds that the combination of its bulk and steep, slick curves poses serious risks.
Tim, George, and Lisa have gathered at Coldfoot to wait out the snowstorm, but Jack - the only driver on the road for the moment - pushes through it to cover the last 50 miles to Deadhorse.
Lisa's pilot car breaks down, leaving her to negotiate the final stretches of snowy tundra alone at night, but she brings her load of truck tires to Deadhorse safely.
Another truck has gone off the road in the bad weather; its driver was thrown free but managed to flag someone down, and he was subsequently airlifted back to Anchorage, Alaska for treatment.
A recovery crew hurries in to get both the rolled truck and its load of pipes back to town without breaking a nearby natural gas line it had almost hit.
Lisa takes on her longest load ever, a set of 80-foot pipes meant for an ocean oil rig, in an effort to prove herself as a potential heavy hauler.
She barely makes it out of Fairbanks ahead of the afternoon curfew for oversized loads, and must then work her way carefully along the road's turns and slopes due to the size of her trailer.
However, both men get rolling just in time, each hauling a load of petroleum products, then run into bad weather that night and stop at Coldfoot after learning that the road has been closed.
As more storms close in on the area and the road crews race to minimize the danger of avalanches, Lisa picks up her next oversized load in Fairbanks: rig mats, a steel framework, and a pickup truck.
Fresh snow buildup on the road makes the turns and slopes very slick, and as she reaches Coldfoot, she learns that the north lane has been closed due to the storm and must wait there for the night.
In Fairbanks, Jack and fellow heavy hauler Carey Hall team up to transport a pair of huge storage tanks that must get to Deadhorse that night.
Encountering steep downhill runs and thick fog, and fighting fatigue on the last stretch, they bring the tanks in on time and then drive into a whiteout on the way back to Fairbanks.
As George waits for repairs on his truck, Tim gets a load of cable spools and prepares to ride in front, practice for eventually making solo runs.
The liquid sloshes back and forth in its tanker, making it hard for him to stay in control on the slopes, and upon reaching the station, he has to adjust his suspension so that his truck will not tear up the unloading platform.
Lisa's preference for faster driving leads Tim and George to put her in front; she soon gets in trouble, stops dead on an uphill run, and has to restart from the bottom as trucks back up behind her.
Jack prepares to take a load of badly needed diesel fuel from Fairbanks to Deadhorse, but he and a mechanic must first free a frozen axle on the trailer.
Reaching the hill where she spun out two episodes ago, she tries a new strategy that allows her to climb it successfully; after clearing the windy Atigun Pass, she arrives in Deadhorse with her load intact.
While hauling his empty fuel trailer back from Deadhorse, Jack loses traction on Atigun and is briefly stranded until a snowplow stops to tow him up to the summit.