Just where the hell is Nicholas "the ginger ninja" Brody? While there is no confusing the former United States marine and congressman (played by Damian Lewis; Life) with a Japanese warrior (it does roll off the tongue far easier than "indecisive red-headed terrorist"), Brody is definitely channelling the mystical skills of near invisibility this week.

As we rejoin the did-he-or-didn't-he drama of Homeland (Fox Movies Premium, tonight at 10.50pm) months after the blast that destroyed half of Langley, the entire CIA (whose headquarters are located in the Virginian town) and their mums are on the hunt for Brody, who was last seen disappearing into the Canadian wilderness. In tonight's season-three premiere, there is no sign of Lewis' flaming barnet and it may be some time before we catch a glimpse of it again.

Saul Berenson (Mandy Patinkin, Criminal Minds) is now acting director of the somewhat depleted intelligence agency and seems ill at ease with his appointment, judging by the amount of whiskey he's knocking back. He is leading the manhunt for the hero-turned-menace and, as he faces the pointing fingers of a congressional grilling, he seems to have decided that the bipolar Carrie Mathison (Claire Danes; Temple Grandin), now off her meds and on the tequila, will be his sacrificial lamb. She is being hung out to dry quicker than Chelsea (born Bradley) Manning's swimming trunks.

Over the course of an award-winning first season and a second season that suffered a critical backlash for its extravagant plot twists and bounding leaps of implausibility, Brody has twice evaded being killed off by the scriptwriters. Will he survive a third attempt as Homeland reclaims its explosive mojo or will he make a grateful exit from what proves to be a damp squib? Stay tuned to find out.

According to thought-provoking documentary The Truth About Exercise (BBC Knowledge, Tuesday at 9.50pm), presented by doctor and journalist Michael Mosley (pictured), we can achieve major health benefits from indulging in just three minutes of high-intensity exercise a week. Even the laziest sofa sloth could make time in a busy schedule of watching television - and writing about it - to do 12 minutes of vigorous exercise a month.

To prove his point Mosley plays guinea pig as he explores new research on the relationship between exercise and weight loss, revealing how certain genotypes can obtain significant improvements in aerobic fitness and insulin response through short sharp blasts of physicality.

While it does have a few fascinating moments, the main problem we have with The Truth About Exercise is that most of Mosley's findings aren't that revelatory and we'd be more than a little surprised if the documentary radically changed anyone's lifestyle. Not to spoil the fun and give away the conclusions (actually, that's exactly what I'm doing) but it unsurprisingly suggests that being active is more beneficial to one's health than sitting around all day on one's jacksie. Hardly enlightening information but at least we now know for sure that the humble chair is a more accomplished killer than the absent Brody.

It's certainly a quick snack for thought but enough of this waffling … I'm off for a three-minute run that should take me right past the gym and straight to the chip shop.