Maab was a Capellan warrior when a landing party from the USS Enterprise visited Capella IV in 2267. Very shortly thereafter, he (backed by the Klingon Kras) staged a coup d'état by challenge, and assumed the title of Teer after murdering Akaar. As part of that succession, he was prepared to kill Akaar's wife Eleen, who was about to give birth to his heir – and she was prepared to die. Startled by this planned murder, Kirk interfered, which resulted in the imprisonment of Eleen and the landing party. Kirk and Spock overpowered their guards, and escaped to the nearby foothills with McCoy and Eleen.
Maab set off in pursuit, and eventually caught up to the landing party. Eleen reappeared; she had given birth, and she told Maab that she'd murdered the baby and the Enterprise crew. Maab seemed prepared to accept this, despite having learned moments earlier from his lieutenant Keel that the Enterprise party was hiding in the rocks within the mouth of the chasm. But Kras insisted on proof, committing a serious social blunder by doubting Eleen's word. He raced towards the mouth of the canyon, and held off the Capellans with a stolen phaser. Ultimately, Maab sacrificed his own life in order to distract Kras long enough for Keel to kill the Klingon. (TOS: "Friday's Child")