The Sea Shepherds kickoff their 10th anti-whaling campaign in the Antarctic (Operation Relentless). As the long range icebreaker Bob Barker gets underway, Captain Peter Hammarstedt knows that the Japanese whalers most likely will be more aggressive than ever (he reflects on last year's campaign, Operation Zero Tolerance, when on February 20th, 2013, the Nisshin Maru rammed the Bob Barker and nearly capsized it while attempting to refuel from its bunker ship, the Sun Laurel). But this year, the Sea Shepherds are going on this campaign without their founder, Captain Paul Watson (who's back on land in an undisclosed location). So leading this campaign will be Captain Peter Hammarstedt, while Captain Sid Chakravarty commands the Steve Irwin, and commanding the Sam Simon is an American, Adam Meyerson. The Steve Irwin and Bob Barker will be patroling in the Ross Sea (Captain Peter is taking a gamble that the whalers will only be in this area and avoid Australia-Antarctic territorial waters because at the same time the campaign is going on, the International Court of Justice is reviewing an action against the Japanese whalers by the Australian government, challenging the claim that the whalers are doing scientific research), while the Sam Simon during this campaign will remain in a holding pattern 400 miles due north of Ross Sea acting as a refueling vessel. Three days into the whaling season, the Steve Irwin's new helicopter nicknamed "Sea Wasp", spots the factory ship Nisshin Maru and one of the three Yushin Maru harpoon ships. Unfortunately, the Nisshin's flensing deck is covered in red and has three minke whales on its deck, meaning four whales are dead. The Bob Barker is only 30 miles away and immediately heads for the factory ship as the helicopter heads back to the Steve Irwin. But in his rush, Captain Peter pushes the Barker's aging engine beyond its limits, and is forced to stop down as the Nisshin gets away. Meanwhile, the Irwin encounters the security ship Shonan Maru No.2 (the same ship that rammed the speedboat Ady Gil four years earlier). The small boats Delta and Humber engage the Shonan by first trying to plug the water cooling vents, but that doesn't work. So they drop prop fouler lines and stop the Shonan, allowing the Irwin to escape.

The Steve Irwin manages to escape from the whalers security ship, Shonan Maru No.2, but soon the Shonan tracks the Irwin down and tails it again. Meanwhile, the Sam Simon lies in wait 400 miles due north of the entrance to the Ross Sea. Its primary job to function as a refueling vessel, so unless the Irwin or Barker need to be refueled, the Simon stays where it is. To the southeast, the Bob Barker sits dead in the water after Captain Peter Hammarstedt pushed the engine too hard. Suddenly, a ship appears on the Barker's radar making 15 knots. The bridge crew debates that if this ship is a harpoon ship, it should go faster. But the Nisshin Maru's top speed is about 15 knots, so Captain Peter thinks the Nisshin is coming towards him. The engine is operational again, but Peter orders that they sit and wait in the fog. All of a sudden, the Yushin Maru No.3 appears and starts to tail the Barker. Peter calls Captain Sid Chakravarty on the Irwin and tells him to send the helicopter ("Sea Wasp") out. The Sea Wasp spots the Nisshin and the other two Yushins. Soon the Barker catches up with the Nisshin, and soon the Irwin joins them. By February 1st, 2014, the Sea Shepherds have been tailing the Nisshin for one full week. Suddenly, all three harpoon ships get behind the Sea Shepherds, looking like they're getting ready to launch an attack to get them off the Nisshin's tail. Captain Peter states that the Yushins attacking the Sea Shepherds in bad weather is something that he and his comrades have not prepared for. He orders one of the Barker's boats, the Gemini, into the water to cut the steel cables the Yushins are towing. After several failed attempts to cut the cables, the Gemini's crew decides to back off because the weather is too rough. Captain Peter tries to hail the Gemini on the radio, but the boat crew refuses to answer him. The Nisshin soon slips out of both visual and radar range. Suddenly, the Yushin Maru No.3 closes in on the Barker's starboard side and collides with it.

The Yushin Maru No.3 has just collided with the Bob Barker (for the second time in almost exactly four years, the first time being during Operation Waltzing Matilda on February 6th, 2010). Crew rush below check the damage, which they find is just badly bent steel ribs, but no water entering the hull. As the Steve Irwin and Bob Barker race towards the Nisshin Maru's last known coordinates, the Sea Shepherds send video of the collision to the media. From his undisclosed location, Captain Paul Watson watches what happened on his laptop. He admits that the whalers more becoming more aggressive because they see that their days are numbered and also worried about the case brought against them in the International Court of Justice. Back in the Antarctic, the Nisshin Maru run into a storm to hide from the Sea Shepherds. Captain Peter calls Captain Sid to send the helicopter out, which does find the factory ship turning due east. The Bob Barker turns to intercept and soon finds the Nisshin within three hours. The harpoon ships are also there, but they don't turn to defend their mothership. Instead, the whalers wait until nightfall to engage the Barker. Both small boats (Gemini and Hunter) are lowered into the water and engage two of the harpoon ships (Yushin Maru and Yushin Maru No.3). They first try to cut the steel cables the Yushins are towing to prop foul the Barker, but don't succeed. So they drop prop foulers of their own to buy time. Soon the Nisshin slips away off the Barker's radar and Peter calls for the boats to return to the ship. As Operation Relentless comes to a close, the Sea Shepherds head back to port. On March 31st, 2014, the International Court of Justice (ICJ) ruled that the Japan's Antarctic whale research program (JARPA II) was not for scientific research and that their operations are illegal. After ten years of fighting, the Sea Shepherds celebrate their greatest victory to date. The whalers this season only killed 271 whales, falling 784 short of their total quota of 1,035. Captain Paul Watson was happy with the ICJ's decision and learned that Japan said it would abide by the ruling. But Paul is convinced that the Japanese whalers want their revenge and will do everything they can to keep going down to Antarctica to kill whales. He made clear if the whalers ever return, Sea Shepherd will be there to stop them. The following year (2014-2015), Japan sent two of its whaling ships on a non-lethal survey in the Southern Ocean Whale Sanctuary. Sea Shepherd admitted the whalers were planning ahead to return to killing whales. The whalers released a new program called NEWREP-A, which calls for the killing of 333 minke whales (no more fin whales or humpback whales will be killed) every year for the next 12 years (until 2027-2028). In 2015-2016, as Sea Shepherd conducted other campaigns around the world, the whalers did return and killed 333 minke whales (103 male and 230 female, 90% of the females were pregnant). Sea Shepherd announced the construction of a brand-new interceptor vessel they named Ocean Warrior due to be completed by September 2016. Most likely it will be sent to the Antarctic to confront the Japanese whaling fleet for the 2016-2017 whaling season. No announcements have been made if the Steve Irwin, Bob Barker, Brigitte Bardot, or Sam Simon will return to battle the whalers.