NBC runs out the string on Undateable tonight, airing a repeat and three original episodes (7, 7:30, 8 and 8:30 p.m., Ch. 5) to bring it to an end.It's not a tragedy. This is a show that was never as good as we hoped it might be.Elsewhere on TV ...Black Box (7 p.m., ABC/Ch. 4): Catherine treats patients with musical problems.Dominion (7 and 8:30 p.m., Syfy): Alex decides he's got to leave Vega.Hell's Kitchen (7 p.m., Fox/Ch. 13): The remaining contestants cook for a football tailgate party.Big Brother (CBS/Ch. 2): The first eviction.Rookie Blue (8 and 9 p.m., ABC/Ch. 4): The execution of a gang leader leads to retaliation.Undateable (8 and 8:30 p.m., NBC//Ch. 5): The guys help Justin pay off his loans for the bar; Danny and Justin compete for a woman.Gang Related (8 p.m., Fox/Ch. 13): Daniel is held hostage by a rival gang.NY Med (9 p.m., ABC/Ch. 4): The doctors treat children who were the victims of a violent home invasion.Rectify (10 p.m., Sundance): Daniel makes a surprising decision.