From Terra Nova Wiki
- "..part of another settlement that split away from Terra Nova. Around here people call them "Sixers", they call them that because they all came through on the sixth pilgrimage"
- — Nathaniel Taylor
The Sixers have an agenda, its purpose still unknown, but Mira, the group's leader, is required to deliver a computer to Lucas Taylor. The Sixers control the quarry, and use the meteoric iron mined at the site to trade to the colony, when it serves their interests. There are Sixers contacts within Terra Nova, including a spy who provides sensitive colony information, and Tom Boylan, a bar owner, who secretly trades with the Sixers. (Genesis, Part 2, Nightfall, What Remains)
The Sixers arrived on the sixth pilgrimage and seemed like the other settlers. Soon after, colonists began noticing their strange behavior and how they were especially interested in the colony's security measures. A hidden cache of contraband weapons was discovered, and the Sixers left Terra Nova, stealing equipment and weapons. Commander Taylor decided against telling Hope Plaza about the Sixers, as he did not know who sent them or why. After Skye Tate's father died of Sincyllic fever, she took her mother to the Sixers, who had a medicine for the disease and blackmailed Skye into being a spy for them, alerting them to convoys to be raided and intelligence about the colony's inner workings. (Genesis, Part 1, Now You See Me, Within)
When Carter was caught siphoning power from the power grid, Mira arrived to negotiate Carter's release, exchanging Taylor's captured soldiers for him. Mira later met with Tom Boylan to trade wild sorghum for medical supplies and a power cell. Mira later devised a plan to retrieve an item hidden in her former residence, having a young Sixer girl, Leah Marcos, allow herself to be captured. Mira and the other Sixers then showed up to demand that Leah be returned, only to have the young girl state she wanted to stay in Terra Nova. Following this, Leah located the item and attempted to escape, but was caught. Mira later allowed Leah's brother, Sam, to return to Terra Nova to be with his sister. (Genesis, Part 2, What Remains, The Runaway)
When Mira learned that Terra Nova's electronics had been disabled by an electromagnetic pulse, she and the Sixers drove an Empirosaur towards the colony as a diversion while Carter and two others broke into the colony to retrieve a specialized computer. Mira and Carter then delivered the computer to Lucas Taylor. Skye provided the Sixers with information about a convoy headed for Outpost 9 which they raided, confiscating all the supplies they were transporting. After Skye is discovered to be the Sixer spy, she tells Commander Taylor that her mother is being held at Mira's camp. Taylor later ordered Curran, who infiltrated the Sixers, to smuggle out Skye's mother. Following this, Mira and the others quickly abandoned their campsite. (Nightfall, Now You See Me, Within)