A moment of full disclosure: this is not your father’s Sherlock Holmes. If you prefer the legendary detective in his traditional deerstalker cap and cloak spouting off soft-spoken observations from the sidelines, then this Guy Ritchie-directed version is not for you. But for anyone who appreciates a fresh, yet reverential, take on a classic story, then the new film starring Robert Downey Jr. as the astute titular sleuth is a film worthy of investigation.

From the opening minutes, “Sherlock Holmes” is noticeably more physical than any previous portrayal of the famous investigator. The adrenaline-fueled and action-packed, yet convoluted and clever movie is as much of a change of pace for the character as it is for director Ritchie — who is usually famous for films about the violent gangster underworld of modern London such as “Snatch” and “RocknRolla.” While Holmes’ bare-knuckle boxing matches and brawls with his enemy’s goons are typical Ritchie, the overall balance of action and intellect, humor and sweetness, brings welcome depth to the film.

Though there are moments when the action feels too outlandish — even for the heightened reality of Ritchie’s Victorian era London — the style of the film grounds Holmes’ world in gritty city reality. Production designer Sarah Greenwood brings her knowledge from past experiences working on Oscar-nominated period pieces such as “Atonement” and “Pride and Prejudice” to excellent use here, setting the sometimes over-the-top action in the appropriately grimy and cluttered slums and jails or spacious and pristine mansions or house of government in the world of 1890s.

In his first time directing a non-modern-day story, Ritchie benefits from the more formal nature of the era to reign in his tendency toward madcap mayhem. The script, by Michael Robert Johnson, Anthony Peckham and Simon Kinberg, further guides the fine line “Sherlock Holmes” plays between the old and the new. The case could come right from one of original author Sir Arthur Conan Doyle’s tales — in this film Holmes and Dr. Watson (Jude Law) his trusty partner in solving crime, must catch a devious serial killer who supposedly uses magic. But the small stakes of the novels are raised to global proportions for the big screen when they discover that the murdering cultist plans to take over British Parliament and then the entire world. Without the raised crisis, the story would not have an impact in theaters. Adding a humorous subplot involving Watson’s attempt to leave his partnership with the eccentric Holmes for his calm fiancé gives just the right amount of additional storylines, humor and emotional resonance for when the mystery plot becomes too confounding.

The quieter moments are when the characters — and the actors who play them — shine. The cast is led by the naturally charismatic Downey, who continues his string of career-restarting performances as he takes on a bit of his own personality with speedy retorts to Watson’s grumblings to his flirtation with former flame Irene Adler (Rachel McAdams). Yet that is not to say Downey doesn’t act in the film. He taps into both the arrogance and alienation Holmes has in his genius and gets both the British accent and mannerisms down pat.

The fun of the film truly lies in Holmes’ personal relationships. Downey’s superb skill is matched by enjoyable performances by Law and McAdams. Each actor bounces their lines off Downey with gusto, occasionally stealing the spotlight — not an easy task when paired on screen with Downey. For all those accustomed to sidekick Watson playing second fiddle to Holmes, Law is intelligent, equally handy in a fight and witty. Watson is merely a more stable version of Downey’s character. And McAdams crafts Irene into a female Holmes-for-hire by the more shady factions of society, the only person who has bested Holmes at his own game. Even supporting actress Kelly Reilly goes toe-to-toe with the others as Watson’s fiancé, Mary.

The only weak link is Mark Strong as the villainous Lord Blackwood. What is meant to be unemotional menace comes off as monotone disinterest at times, and he never seems to throw Holmes off his game, the true test of a well-matched foe for the detective. Hints at the appearance of Holmes’ classic nemesis, Professor Moriarty, were more enticing.

Although the token “evildoer” was no match for the wit and skill of the unbeatable Sherlock Holmes, the film still has enough nail-biting moments to leave the audience consistently in suspense. From the updated action-packed style to the quality and pure enjoyment of the acting, “Sherlock Holmes” feels as fresh as it was meant to.