“Doctor Who” (8 p.m., today, BBC America) returns with a new Doctor. Matt Smith takes over the role as the time traveling world-saver and becomes the 11th actor in the title role of the long-playing series.

This season, the Doctor arrives in the backyard of a fearless little girl who can hear strange noises through a crack in her bedroom wall. Following the logic of this fantasy, the Doctor quickly determines that the crack is not in the plaster but in the universe itself, threatening the planet with imminent destruction.

After promising to return “in five minutes,” he hops into his Tardis time machine only to land in the backyard 12 years later, when both the girl, Amy Pond (Karen Gillan), and the global threat have matured substantially.

Smith brings a tongue-in-cheek flippancy to his Doctor as he improvises MacGyver-like to save the day with only 20 minutes to spare.

This episode was written by Steven Moffat, author of some of the most acclaimed “Who” installments and who wrote the script for the forthcoming Steven Spielberg adaptation of “Tintin.”

• don’t know if it has to do with time travel, but Smith has an uncanny resemblance to a young Michael York (“Cabaret”).

• “Death and Taxes” (7 p.m., today and Sunday, CNN) looks at the curious case of Joe Stack, a disgruntled Texan who flew his plane into a federal building in Austin and left a long note of grievances against the government and corporations.

• Andie MacDowell, Daniel Sunjata and Ashley Williams return in “The Front” (8 p.m., today, Lifetime), adapted from a novel by Patricia Cornwell. Originally broadcast last week, Cornwell’s “At Risk” (6 p.m.) also airs.

• From “Foyle’s War” to “Island at War,” “Masterpiece” (8 p.m., Sunday, PBS, check local listings) has offered different views of England during the World War II years. Add “Small Island” to this list of memorable programming.

Based on an acclaimed novel by Andrea Levy, “Island” recalls the Jamaican immigrants who arrived in Britain during and after the war and the clash between islanders divided by a harsh history of slavery and subjugation but linked by language and allegiance to king and “motherland.”

With the war and two very different islands as a backdrop, “Small” relates the overlapping stories of two headstrong women. Hortense (Naomie Harris) may be poor and illegitimate, but she compensates with a haughty manner, a fierce dedication to self improvement and a fixation on a better life in England. The daughter of British pig-farmers, Queenie (Ruth Wilson) displays none of her white countryman’s condescension or prejudice against arriving Jamaican soldiers and airmen. Indeed, her decision to greet them with an open mind and open arms will have rather dire consequences.

As their parallel stories unfold and later converge, both women share unusual and unfulfilling marriages and reflect the shifting dynamic between men and women, black and white, English and “colored” in a changing world.

Presented in two 90-minute installments, “Small Island” has all the elements of great melodrama, an epic sweep, intimate love stories and memorable characters whose actions and attitudes challenge the course of an Empire. “Island” concludes next week.

• While Lifetime has aired murder mysteries over the past two weekends, the ABC Family network poaches a bit of their territory with “Beauty & the Briefcase” (7 p.m., Sunday, ABC Family). Hilary Duff stars as a fashion writer who goes undercover to see if she can find true love in the world of big business.

• “Lost Gold of the Dark Ages” (8 p.m., Sunday, National Geographic) celebrates an amateur metal-detector enthusiast who stumbled upon a huge cache of Anglo-Saxon jewelry and treasure.

Today’s highlights

• The voices of Robert De Niro and Will Smith animate the 2004 cartoon feature “Shark Tale” (7 p.m., ABC).

• Mixed martial artists mix it up on “Strikeforce Nashville” (8 p.m., CBS).

• Ryan Phillippe hosts “Saturday Night Live” (10:30 p.m., NBC), featuring musical guest KeSha.

Sunday’s highlights

• “Dateline” (6 p.m., NBC) looks at efforts to revive Detroit.

• Alan Cumming, Tahmoh Penikett and Laura Vandervoort star in the 2010 four-hour fantasy “Riverworld” (6 p.m., Syfy).

• Reba McEntire hosts the Academy of Country Music Awards (7 p.m., CBS).

• A famous chef gets his own variety showcase, “The Emeril Lagasse Show” (7 p.m., Ion). His first guest: Martha Stewart.

• “Nick News with Linda Ellerbee” (7:30 p.m., Nickelodeon) examines the emerging global water crisis.

• Bloody Action on Peleliu on “The Pacific” (8 p.m., HBO).

• Davis discovers that his musical integrity has its price on “Treme” (9 p.m., HBO)

Cult choice

A deranged passenger (Robert Walker) involves a tennis star (Farley Granger) in a murder plot in director Alfred Hitchcock’s 1951 thriller “Strangers on a Train” (7 p.m., today, TCM). Leave it to Hitchcock to cast his own daughter as bespectacled murder victim.