As part of an exchange program, a Klingon officer named Kurn arrives on board the U.S.S. Enterprise. He soon informs Worf that they are brothers, having been separated shortly before their parents were killed in a Romulan attack on the Khitomer Outpost. Kurn tells Worf that new evidence has surfaced which indicates that their late father, Mogh, aided and abetted the Romulans in the Khitomer assault which resulted in the deaths of 4000 Klingons. To defend his family's honor, Worf goes before the Klingon High Council to challenge the treasonous accusations. Accompanied by Kurn, who serves as his brother's cha'Dlch (a second who will defend him during the trial), Worf faces the high council. During a recess, the council leader, K'mpec, asks Worf to drop his challenge, but he refuses. Elsewhere, Kurn is seriously wounded by two Klingon assassins after Duras, another council member, requests that he betray Worf and Kurn refuses.
