Highly complex or intricate and occasionally devious:
— Tortuous legal procedures.
— Tortuous negotiations lasting for months.

synonyms: Byzantine, convoluted, involved, knotty, tangled.

Roget 940: dishonest, dishonorable; unconscientious, unscrupulous; fraudulent etc. 545; knavish; disgraceful etc. (disreputable) 974; wicked etc. 945.    false-hearted, disingenuous; unfair, one-sided; double, double-hearted, double-tongued, double-faced; timeserving^†, crooked, tortuous, insidious, Machiavelian, dark, slippery; fishy; perfidious, treacherous, perjured.    infamous, arrant, foul, base, vile, ignominious, blackguard.    contemptible, unrespectable, abject, mean, shabby, little, paltry, dirty, scurvy, scabby, sneaking, groveling, scrubby, rascally, pettifogging; beneath one.    low-minded, low-thoughted^†; base-minded.    undignified, indign^†; unbecoming, unbeseeming^†, unbefitting; derogatory, degrading; infra dignitatem [Lat.], beneath one's dignity; ungentlemanly, ungentlemanlike; unknightly^†, unchivalric^†, unmanly, unhandsome; recreant, inglorious.    corrupt, venal; debased, mongrel.    faithless, of bad faith, false, unfaithful, disloyal; untrustworthy; trustless, trothless^†; lost to shame, dead to honor; barratrous.    ... show more

Roget 248: convoluted; winding, twisted etc. v.; tortile^†, tortive^†; wavy; undated, undulatory; circling, snaky, snake-like, serpentine; serpent, anguill^†, vermiform; vermicular; mazy, tortuous, sinuous, flexuous, anfractuous^†, reclivate^†, rivulose^†, scolecoid^†; sigmoid, sigmoidal [Geom.]; spiriferous^†, spiroid^†; involved, intricate, complicated, perplexed; labyrinth, labyrinthic^†, labyrinthian^†, labyrinthine; peristaltic; daedalian^†; kinky, knotted.    wreathy^†, frizzly, crepe, buckled; raveled etc. (in disorder) 59.    spiral, coiled, helical; cochleate, cochleous; screw-shaped; turbinated, turbiniform^†.    ... show more

Roget 528: concealed etc. v.; hidden; secret, recondite, mystic, cabalistic, occult, dark; cryptic, cryptical^†; private, privy, in petto, auricular, clandestine, close, inviolate; tortuous.    behind a screen etc. 530; undercover, under an eclipse; in ambush, in hiding, in disguise; in a cloud, in a fog, in a mist, in a haze, in a dark corner; in the shade, in the dark; clouded, wrapped in clouds, wrapt in clouds^†; invisible etc. 447; buried, underground, perdu [Fr.]; secluded etc. 893.    undisclosed etc. 529, untold etc. 527; covert etc. (latent) 526; untraceable; mysterious etc. (unintelligible) 519.    irrevealable^†, inviolable; confidential; esoteric; not to be spoken of; unmentionable.    obreptitious^†, furtive, stealthy, feline; skulking etc. v.; surreptitious, underhand, hole and corner; sly etc. (cunning) 702; secretive, evasive; reserved, reticent, uncommunicative, buttoned up; close, close as wax; taciturn etc. 585.    ... show more

Marked by repeated turns and bends:
— A tortuous road up the mountain.

synonyms: twisting, twisty, voluminous, winding.

Not straightforward.