Alert: Spoilers follow from the debut episode of CBS drama “Watson.”

Even the famously intelligent detective Sherlock Holmes would not have anticipated this version of Professor Moriarty.

The series “Watson” unveiled its surprising villain during the CBS premiere on Sunday, set in the world of Sherlock Holmes and narrated through Dr. John Watson (Morris Chestnut). The role of Moriarty is portrayed by Randall Park, who is dressed in a polyester polo shirt.

Having a notorious criminal mastermind don casual workwear was a shock, even to Park, who is 50 years old and recognized as the easy-going dad from six seasons of ABC’s comedy “Fresh Off the Boat.” He also took on the role of a laid-back video-store manager in Netflix’s “Blockbuster,” which also required him to wear a polyester polo.

“I’m usually cast as friendly, relatable characters. So, receiving that call was a surprise, but a delightful one,” Park shared with YSL News regarding his wicked character. “The thought of portraying a villain excites me.”

Park has previously played antagonists too: he depicted North Korean leader Kim Jong-un in the notorious comedy “The Interview” from 2014. However, that role leaned into dark humor. Even in Marvel’s “WandaVision,” his character, the compliant FBI Agent Jimmy Woo, is portrayed with a comedic tone. In contrast, Moriarty is played very seriously.

“They were searching for someone who appears to be an ordinary guy,” Park explains. “But could this seemingly regular individual actually be a dangerous, psychotic supervillain?”

How does Randall Park’s Moriarty make his appearance in ‘Watson’?

Both Moriarty and Holmes were thought to be dead in “Watson” following a violent opening that ended with a gunshot and a fall into a frigid Swiss waterfall. Watson jumps in to rescue his best friend but suffers a severe blow to the head from a rock. After recuperating, Watson takes charge of Pittsburgh’s Holmes Clinic, focusing on treating rare medical conditions due to his friend’s generous bequest.

However, Moriarty turns out to be alive, subtly emerging in the series’ closing moments while on Pittsburgh’s famous Duquesne Incline cable car. Watson’s assistant, Shinwell Johnson (Ritchie Coster), is taken aback to discover the overlooked villain dressed in a white polo featuring a puzzling logo, “Always & Everywhere.”

“I thought he’d look different,” says Shinwell, delivering a box of clinic DNA samples. Moriarty then delivers a monologue about a germ that “might even make its mark in history” in Pittsburgh before leaving with a sinister grin.

“That friendliness conceals something much darker,” comments Craig Sweeny, executive producer and writer of “Watson.” “He’s the sort of guy who could repair your washing machine or fix your disc drive. Many great actors were interested in this role, but Randall was uniquely appealing.”

Who is Moriarty in the Sherlock Holmes lore?

Professor James Moriarty serves as Sherlock Holmes’ formidable foe in the well-known detective stories by Sir Arthur Conan Doyle, often described as moving “in a strangely reptilian manner.” Sir Laurence Olivier portrayed him in the 1976 film “The Seven-Per-Cent Solution.” Andrew Scott won acclaim as the dapper Jim Moriarty in the BBC series “Sherlock,” which starred Benedict Cumberbatch from 2010 to 2017.

Sweeny kept Moriarty’s character a secret, referring to him only as “Pittsburgh Dad” while crafting the script and even on the sign outside Park’s trailer on the Vancouver set.

“It wasn’t the typical Marvel secrecy with NDAs,” Park notes. However, the confidentiality helped him connect with the character every day. “Each time I saw ‘Pittsburgh Dad’ on the call sheet, it was a reminder of my mission.”

Moriarty will feature throughout the “Watson” season clad in different but appropriate office attire. “He really isn’t into fashion,” Park mentions. He assures fans that a face-off between Watson and Moriarty will happen by the season’s finale. Even when he isn’t on screen, Moriarty’s subordinates are executing his orders, leaving a sense of his ominous influence. “Just like the shirt suggests, he’s always present and always watching,” Park remarks.

Chestnut appreciates the introduction of his rival on “Watson.”

“In the final scene, you notice that subtle smirk and the mischievous essence of Mr. Park,” Chestnut comments. “That’s merely a glimpse of what’s to come.”