While recent motion-picture successes seem to be dominated by superheroes such as Batman, James Bond, Iron Man, Indiana Jones, Jason Bourne, and Hellboy, there appears to be a great deal of energy left in the film life of the man who was described by his closest friend as “the best and wisest man whom I have ever known,” which indicates that Sherlock Holmes is also a superhero, though of a slightly different sort.

Warner Bros. is scheduled to start filming “Sherlock Holmes” later this year — one of two major films scheduled for release in 2010 about Holmes and Dr. John H. Watson — and it’s Iron Man himself, Robert Downey Jr., who will improbably play the world’s first private detective. This is a project for which the word “improbable” comes screaming off the page to sink its talons and teeth into the soft tissues of the brain.

The announced director and screenwriter is Guy Ritchie, whose predominant toehold on fame is for being married to Madonna, whom he plans to cast as the unfortunate victim of a serial killer who is being chased around Queen Victoria’s London by Holmes. Short of casting Danny DeVito as Dr. Watson, the least likely candidate for that role must be Jason Statham, a wonderful actor but someone so hard that the softest thing about him is his teeth. He starred in “The Bank Job,” released earlier this year, and if you missed it, as too many people did, you missed the best crime and suspense film of the past several years.

Mr. Downey has already admitted that his mind is a total blank when he tries to figure out how to play Holmes. He was quoted in the Montreal Gazette: “I’m like: Okay, they’re going to pay me to do this movie and I don’t have a (darned) idea in my head.” He is also having trouble with an English accent, adding, “I hope I figure this out before we start shooting.” It is safe to think that he speaks for us all.

Columbia starts shooting its competing “Sherlock Holmes” film next month in a scenario that makes the Warner film seem controlled and rational. The reports are that there is not yet a script, which some might regard as a handicap when the cameras start rolling, but screenwriter Etan Cohen (no, not one of the Coen brothers) is working on it.

This one stars Sacha Baron Cohen as Holmes and the apparently indefatigable Will Ferrell as his roommate and amanuensis, and the goal will be to accurately use Victorian forensics and slang. Why being authentic about the details seems important while producing a gigantic farce eludes me, but I have no doubt that a very smart young fellow at the studio is snapping his suspenders with excitement at the prospect.

* * *

Statistics involving Nora Roberts are enduringly entertaining because they are so incredible. Some time ago, I reported that she sells a book every eight seconds — 365 days a year. On top of that, her fans can love her without having to read her books.

Lifetime Television announced that four of her books will be adapted for TV next year due to the extraordinary popularity of earlier adaptations of her novels, which had 34 million viewers. I have no plans to be watching any of these made-for-television movies. You can call that ignorance or apathy but, if you do, I won’t know and I won’t care.

Speaking of adaptations, how is this for an ironic twist? One of America’s greatest mystery writers, Robert B. Parker, has enjoyed enormous success for more than three decades writing about Spenser, his Boston-based private eye. While the plots are not as complex as assembling a bicycle on Christmas morning, the books are unfailingly lively and amusing because of the witty, snappy dialogue.

This tone seduced the actress Helen Hunt, who asked Mr. Parker to create a female character in the style of Spenser so that she could portray her in the movies. He agreed and wrote “Family Honor” (1999), a novel about Sunny Randall, a former police officer who now works as a private detective. He has written six novels about the wisecracking sleuth, all of which have enjoyed stays on the best-seller list, including the recent “Spare Change,” but, of course, no films have been made.

This does not especially trouble the author. “Nothing ever dies in Hollywood,” he comments on his Web site, “though the birth rate is also low.”

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the Best American Mystery Stories. He can be reached at ottopenzler@mysteriousbookshop.com.