'Harry Potter' child star talks about Daniel Radcliffe's 'insane' letter

New Harry Potter series star Dominic McLaughlin spilled the beans from the moment he received a letter from OG Harry Potter star Daniel Radcliffe.

The child actor said he was shocked by the unexpected gesture and described the note as "insane."

Recounting the scene, McLaughlin, who will play the titular wizard in the new adaptation of J.K. Rowling’s books, revealed he received the letter while on a train heading home to Glasgow.

"It was insane," he said enthusiastically, adding, "My Dad tapped me on the train and just gave me this letter."

"I read it and then I got to the bottom, and it said, 'Dan R.' I was going mad, but I had to [keep cool]. I was on the train," the much-anticipated HBO series' star recalled during an interview with the BBC show Saturday Mash-Up! Live.

McLaughlin's wholesome reaction to the letter came days after Radcliffe, 36, revealed last month that he had penned a letter for the younger actor.

"I just see these pictures of him and the other kids and I just want to hug them," he said. "They just seem so young. I just look at them and say, 'Oh it’s crazy I was doing that at that age.'"

"But it’s also incredibly sweet, and I hope they’re having a great time,” the English actor added.

For the unversed, McLaughlin was announced as Harry Potter in May and has been filming on the HBO series over the summer.

As for Radcliffe, he will always remain the original Harry Potter, having played the character in the eight Warner Bros. films from 2001 to 2011.