For a second season, John Noble (“Fringe”) lends his slightly ominous presence to “Dark Matters: Twisted but True” (9 p.m. Saturday, Science), a series that exposes shocking scientific studies, theories and experiments that crossed the boundaries of decency and morality — or at least good taste.

One of tonight’s three tales looks at hero aviator Charles Lindbergh’s detour into medicine and theories about eugenics. His interest in the protection of “superior” races and the culling of weaker, “degenerate” races brought him perilously close to being a Nazi.

In another strange case, a 19th-century doctor treats a man with a bullet wound, which allows him to look into the man’s stomach during the act of digestion. This peculiar vantage point added greatly to medical science, but after some years, the patient began to justifiably feel like a prisoner — an unwilling participant in an endless experiment.

A third segment recalls a depressed Hungarian musician’s composition, “Gloomy Sunday,” a song that appeared to have inspired dozens of suicides. The show makes a half-hearted effort to link the song, its lyrics and its minor chord composition to these desperate acts, but concludes that they may have had more to do with Hungary’s bleak social and economic picture during the 1930s. “Gloomy Sunday” became an international hit for several artists, most notably Billie Holiday.

”Dark Matters” offers a thought-provoking mix of history, science and human weirdness. If I must quibble, it’s with the more whimsical, animated special effects that visually clash with the show’s macabre tone.

Saturday’s other highlights

• A young girl balances her gymnastics dream with the demands of schoolwork in the 2012 family movie “An American Girl: McKenna Shoots for the Stars” (7 p.m., NBC).

• The Hallmark Channel will spend the weekend pretending that it’s Christmas, with offerings like “The Most Wonderful Time of the Year” (7 p.m.) and “A Princess for Christmas” (9 p.m.). Check listings for more holiday baubles.

• The host of “Take Me Out” returns to standup on “George Lopez: It’s Not Me, It’s You” (9 p.m., HBO).

• “Oddities: San Francisco” (8 p.m., Science) turns up a strange diorama.

• “The Firm” (9 p.m., NBC) concludes as the Walker trial begins.