Law & Order, 9.35pm, Ten It has been 18 years since Law & Order chung- chunged its way into the world, and long- time fans will be pleased to see Jack McCoy ( Sam Waterston) finally promoted to district attorney after the actor who played the previous one, Fred Thompson, made an ill- fated bid to become the Republican presidential candidate. There are also two new cast members, played by Jeremy Sisto and Linus Roache. What stays the same is the continued focus on high- profile, big- picture cases rather than ordinary murders, which makes for enjoyable viewing, but it’s not a patch on when the show was in its prime. Enough Rope, 9.35pm, ABC1 Watch out, Denton’s about. Yes the little nipper is back, nipping as only he can, at the heels of our thorniest issues. And if thorny issues do indeed have heels, I’m sure Andrew Denton, pictured, will be the one to nail them. Tonight’s episode, Angels and Demons, is something really quite different for the former Boy Wonder: an investigation into mental illness. Denton tells us that he wants to know what it feels like to lose your mind and if, having lost it, you can find it again. Brave, thoughtful and insightful television. 30 Rock, 11.30pm, Seven This sitcom is an odd beast, mixing the absurd, genre- defying flourishes of Arrested Development with realistic characters. It works well, possibly because the world of TV is absurd anyway. This episode introduces recurring character Devon Banks ( Arrested ’ s awesome Will Arnett) as a gravelly voiced rival to executive Jack Donaghy ( Alec Baldwin).