Tonight in HD: April 20 UPDATED*

Season Highlight: Titanic (TV One, 8.30) Political strife in Belfast interferes with the construction of the new liner, Titanic; a young engineer takes the opportunity of a lifetime; and class battles are overshadowed by a looming iceberg. Quipped Encyclopedia Titanic of episode two: “This production is beginning to make me fear the onset of Alzheimer’s. I just can’t follow it. Younger or more astute viewers than me may have less trouble in following the plot-lines, but I can’t help thinking that better continuity and editing, and a smaller cast of characters, would make this a much easier drama to comprehend. The weekly sinking bursts upon us as just we are saying ‘Hang on, what’s going on here?’ Too late. They’re either suddenly all on deck, in the boats, or resigned to their fates.” And it seems the programme makers agree: according to The Guardian, the producer of the £12m mini-series “has admitted the show’s nonlinear storytelling, which sees the ship hit the iceberg in each episode, may have put viewers off the Julian Fellowes-scripted drama that has foundered in the ratings.” ✮✮✮

Home & Away (TV3, 5.30) Leah is left unsure about her feelings for Brax; John and Gina give their marriage another go; Ruby, upset about Romeo, runs into the arms of a untrustworthy surfer. ✮✮

Friends (TV2, 6.30, R) Oh my God — Janice is back, which stresses Chandler, while Ross plays rugby to impress Emily, with painful results. ✮✮✮✮

Shortland Street (TV2, 7.00) Lana’s tempted by an unexpected offer; Vasa’s out of the frying pan and into the fire; Vinnie throws Bree to the wolves. ✮✮✮

Glee (TV3, 7.30, 5.1) When Will tries to plan a special surprise for Emma, he enlists the glee club to help him sweep her off her feet. ✮✮✮

The Best of the Graham Norton Show (TV3, 8.30) Highlights from the latest season. ✮✮✮✮

The Vampire Diaries (TV2, 10.30) Sheriff Forbes delivers disturbing news to Alaric and Elena about a recent murder weapon; Caroline is heartbroken when unable to stop a tragedy unfold. ✮✮✮

Numb3rs (TV3, 12.15, 5.1) A weapons smuggler stands trial for the murder of a FBI informant, but he is acquitted despite a strong case against him — which leads Charlie to suspect jury tampering was involved. ✮✮

Persons Unknown (TV3, 1.10, 5.1) The group feel uneasy after learning they’ll be restricted to the hotel and come across personal items in their rooms. ✮✮

* Note: The SoHo premiere of How to Die in Oregon will air on April 27, not tonight as previously posted.