Krasinski's Ryan is introduced as a boyish-looking, office-bound intelligence analyst, albeit one with a helpful background as a Marine who saw action abroad. He immediately chafes when faced with a new section chief, the crusty James Greer ("The Wire's" Wendell Pierce), who has been demoted into a gig that he clearly loathes.Greer, of course, will eventually become Ryan's friend and mentor, but for now, he's the obstacle standing between him and aggressively responding to an alarming pattern of suspicious money transactions in Yemen — evidence, Ryan deduces, that a major terrorist plot might be in the works.Ryan will eventually find himself operating in the field, coming face to face with someone who describes him (in perhaps the show's best line) as "a wolf that plays at being a sheep." He also embarks on a new romance with the well-connected Cathy (Abbie Cornish), which frankly feels like a distraction given everything else the dude has on his plate.Then again, the bill of fare served up by producers Carlton Cuse ("Lost") and Graham Roland, who adapted the series, has a pretty conventional feel despite its handsome, globetrotting trappings and cinematic qualities. At times the narrative plays like another season of "24," albeit with a protagonist who (his resourcefulness notwithstanding) is too new to the spy game to start breaking any thumbs.Following in the footsteps of Alec Baldwin, Harrison Ford, Ben Affleck and Chris Pine's more recent junior-edition portrayal, Krasinski comes armed with a helpful vulnerability honed during his "The Office" days, as well as recent hit credentials from the movie "A Quiet Place." One of the nice things about Ryan has always been that he's a reluctant hero, not another Bond or Bourne, a persona that Krasinski admirably conveys.Still, those attributes — and the star's innate appeal — can't fully liberate "Jack Ryan" from the nagging sense the show represents a once-over-lightly version of this well-trodden material, intended to give a lift to Amazon's streaming service by trading off a well-known literary/screen name.There is, obviously, a lot of that particular program-development strategy going around these days, and Amazon has already given the show a vote of confidence by ordering a second season. But despite the worthwhile elements that "Jack Ryan" possesses, the whole thing feels a bit too much like a sheep in wolf's clothing."Tom Clancy's Jack Ryan" premieres Aug. 31" on Amazon.