The planet where, in 2386, the former Borg drone Icheb is lured into a trap and stripped of his implants, and where Seven of Nine finds him too late to save him.
Vergessen is a planet seen in the opening flashback of the Picard episode Stardust City Rag. Thirteen years before the main events, Icheb, by then a Starfleet officer who also helps the Fenris Rangers, is captured there and strapped down in a makeshift operating theatre.
A surgeon cuts out his Borg components without anaesthetic for sale on the black market, complaining that his cortical node is missing; he had given it to Seven of Nine years earlier aboard Voyager. Seven shoots her way in and kills those responsible, but Icheb is beyond help, and at his plea she ends his suffering herself.
The killing drives her pursuit of Bjayzl, the trader in ex-Borg parts who had betrayed them both, and explains the bitterness she carries when Picard meets her again. The planet's name is the German word for forgotten.