"He's an opportunist, rather than a career burglar, so he doesn't intend to scare anybody," says Dennis, 60, explaining his character's actions.
"He hopes to be burgling an empty house and worries about people being insured. He's a burglar with a conscience!"
Due to prior commitments (he's currently on a nationwide theatre tour of The Perfect Murder, which was at Glasgow's King's Theatre last week), Dennis only appears in two episodes initially, although he's set to return to screens in June.
As brief as his introduction is, the scenes set a strong foundation for the character.
"He's disturbed burgling Gail's house and tries to make out he's fixing the gas meter," Dennis reveals. "He gets chased by Kylie and you later find he's been caught."
As a victim of crime, Gail winds up visiting him in prison. "She's thankful for his apology," says Dennis, referring to the 'restorative justice' storyline that will play out over the summer months - and lead to an unexpected understanding between the pair.
Dennis is "absolutely thrilled" to be working with Helen Worth, who's played Gail since 1974.
"I think she's a great actress," he notes - and it also means there are sure to be run-ins with the Platts. "They're a family who are really at the hub of the street, so that gives me a lot of potential as an actor," Dennis adds.
While Michael might not mean any physical harm to his victims, he doesn't understand the effect his actions have. "And the violation you feel," says Dennis, whose home in London was burgled three years ago.
His wife, Claire, was about to give birth to their son, Tom, and the car, which was also been stolen, had been packed with baby clothes and a camera.
"That was the least of our troubles, it was the idea of them being in the house," says Dennis, whose daughter Eleanor, then two (he also has a grown-up son, Philip, from his first marriage to Lynne Webster) had been asleep at the time.
The police found the perpetrators but they weren't prosecuted.
"It was one of those things where it became so frustrating," he recalls. "We lived right on parkland and it meant that people could get over the fence quite easily."
A lifelong fan of the show, Dennis became associated with the soap back in the 80s, after doing a Mavis impersonation to fellow impressionist Dustin Gee's Vera.
He and Gee had a comedy double-act and their own show, The Laughter Show, from 1984 until 1986, the year Gee died following a heart attack.
"When we did that, Liz [Dawn, who played Vera Duckworth until 2010] said to come down and see the set. It's a dream come true for me to be playing a serious role in the soap."
Dennis was on his way to Bath with The Perfect Murder when he received the call from his agent saying the soap's bosses were interested in seeing him for a screen test.
Fortunately, former cast member Gray O'Brien [who played Tony Gordon] also happened to be on tour with the play and helped him with his lines. "He was Gail for the week, he even did her voice, and got me absolutely word perfect."
The preparation paid off; Dennis was on set a week later.
"It was a fantastically exciting whirlwind," he says, admitting that he didn't even suffer first-day nerves as "I only had to run down the cobbles".
The second day proved more nerve-racking: "It was a very short scene but you have to establish your character very quickly and hit the ground running."