The next episode of the BBC One drama sees the actor's character Connor Mulgrew endure more tough times with his alcoholic mum Christine (Laurie Brett). However, it's not all doom and gloom as viewers will also see his relationship with Imogen Stewart (Kirstie Steele) continue to blossom.
When Imogen's outrageous mother Sally drunkenly gatecrashes her birthday party at the schoolhouse, Connor steps up to the plate by asking her to leave. Feeling protected by her fellow student, Imogen then decides to share a big secret with Connor…
Digital Spy recently caught up with Shane to hear more about episode four and his time at Waterloo Road so far.
As a newcomer to Waterloo Road, how well have you settled in?
"It's all gone really well. It can be a bit intimidating when you're joining a show that is so high-profile and established, so when I came in and did the read-through it was all a bit surreal! But I feel like I've adapted to it really quickly, especially as everyone's been so nice and welcoming.
"Even though I've only just come on screen, I've been filming now for five or six months, so I do feel like part of the mould now. Also, there are new pupils who joined after I started, so I don't feel new anymore."
How did you feel when you got the part?
"I did my audition and that went well, and then I got my callback. My agent called me three weeks after that, so by that point I'd put it to the back of my mind, because I hadn't heard anything yet and I was auditioning for other things. It was about half eight in the morning and my agent explained that I'd got the part.
"It was a bit of a shock, really - I flew out of my bed cartoon-style! My agent was telling me all of this information about filming dates, but I was blank and not really taking any of it in. So she said, 'Go and celebrate with your friends and family, and I'll call you back tomorrow and give you the fine details!'
"I went downstairs and told my mum, who was pottering around in the garden, and she was just as shocked as me but obviously really happy as well."
Had you watched Waterloo Road much before joining the show?
"Yeah, I'd seen it on and off for a few years, so I knew the general gist of the show and the kind of storylines it covers. I knew that the stories are quite dramatic and tackled well. It was a drama that I really did like, but I hadn't watched it much over the past year, so once I got the part, I went back and started watching it from the start of series seven to catch up."
Who was the first person you made friends with on set?
"For me, it was probably Kirstie, who plays Imogen, because we had a rehearsal and our costume fittings together. I met her first, and because she was the only person that I really knew, we just gelled - and then obviously we worked quite closely together as well. So we got to know each other a lot, and we're really good friends now."
Pictured: Connor and Imogen in Waterloo Road.
In the past, you've done short films and theatre. How does Waterloo Road compare?
"It's a massive jump, really. I'd trained for a few years, but I thought that if I was ever lucky enough to get to a point like this, it'd be another good few years down the line.
"The previous projects had been mainly for experience, and to get a little bit on my CV. Then Waterloo Road came along, and I was taken aback with how much things can change. Things have definitely changed a lot for me since getting this job in April, so it's brilliant."
A lot of your scenes are obviously with Laurie Brett, who we all know from EastEnders. What is she like to work with?
"Laurie is amazing and so talented. She makes me laugh so much on set, and we get on great. When you're working with someone as established as Laurie, you get a lot of advice and tips about the industry. I'm taking that in like gold dust.
"I've been able to learn so much from Laurie. She's given me lots of little hints and tips, and I feel blessed to be able to work with her so closely."
When it comes to the alcoholism plot, how have you found tackling such a challenging storyline?
"Well, if me and Laurie have a big scene for the storyline, we normally go through it together beforehand. We'll discuss what we both want to do with the scene, and then find a mutual ground over the way it should be.
"We've also had some really intense scenes where it's not even a spoken thing - you just go for it, and if there's anything you don't like on the first take, you just adjust it and fix it on the second take. We work really well together, and I think we've been able to find a place where we're both doing what the other wants to in each scene."
In episode four this week, Christine seems to be getting even nastier towards Connor. How does he cope with that?
"He doesn't, really! Having said that, he has been brought up with this since he was younger, so it's not something that's new to him. It's his normality, really, to have Christine screaming at him due to her alcohol problems.
"It's normal for him to see his mum in these conditions, even though he's saying to her constantly that she needs to help herself. It's also screwed him up emotionally a little bit, so you'll see that come out as the episodes progress."
This week, we also see Imogen have some trouble with her mum Sally, don't we?
"Yeah - Imogen and her mum are really like chalk and cheese! Imogen is quite a quiet person, but her mum is this glamorous, flamboyant, happy-go-lucky character, who comes to the school to help out with Tariq's kayaking fundraiser.
"Imogen wasn't expecting to see her mum there, and you'll see that Sally is quite a flirty character, which attracts the attention of some of the boys in the school. That embarrasses Imogen, and then later Sally ends up turning up to Imogen's birthday party at the schoolhouse with one of the students, Gus. Imogen's mortified to see her mum there, especially as she's a little bit tipsy and in a skinny dress!"
Pictured: Imogen's mum Sally with Gus.
Things seem to be going well for Connor and Imogen at this point. Why do you think they've become such a good match?
"I think the two of them just find each other really interesting. At first, Connor was quite closed-off and introverted, so he didn't really notice that Imogen was interested in him.
"But what you'll see in episode four is that Imogen has got a secret to tell Connor. She feels comfortable to tell him at the party at the schoolhouse, because Connor has stood up for her by asking Sally to leave, so she feels protected.
"They're both closed-off people, but they start letting each other in. I think it's just a natural attraction to each other."
What's coming up for them afterwards? Is it plain sailing from then on?
"There's some really happy scenes and a lot of really romantic stuff coming up between now and episode ten. But then again, Connor has got a lot going on in his home life, and Imogen has her own problems as well. It's a bit of a rollercoaster at times. Mostly it's good, but there are some times when it's starting to look a bit rocky as well…"
Do you share many similarities to Connor?
"Not really, because I'm quite a sociable person. A lot of the younger cast here at Waterloo Road go out and we do things after filming, while Connor keeps himself to himself and doesn't really mix with the other pupils.
"Connor doesn't have a lot of friends, but he likes it that way - I don't think he likes people knowing too much about him. So we're not really similar in that respect."
Can you share any behind-the-scenes stories from filming?
"Well, I broke my arm about a month into filming! It was basically the most pathetic fall ever - I tripped in my dressing room over a small table!
"Also, we all do get the work done here on set, but sometimes you can't help it and you get the giggles. You end up having to go and compose yourself, so there's loads of things like that happening! It's really relaxed on set, as well. Everyone has a good laugh together and chats away to everyone else. But when we do start work, we do take it seriously and everyone pulls it together."
We've heard that you're originally from Ireland, so how long have you been living in Scotland for?
"I moved over here to Scotland when I was 7, so it's been about 12 and a half years now. But I still have a lot of family in Ireland, so I go over quite a lot. My dad's still there, and I've got aunties, uncles and cousins. I go over maybe three times a year, but obviously not this year because I've been so busy."
How do you feel about Waterloo Road moving to Scotland?
"It's a big thing to move an established show, but I think they've done it so cleverly and it's really exciting for Scotland. It's opened up a lot of jobs, so it's great for the filming industry up here."
What are the standout episodes for Connor we should be watching out for?
"There's quite a few. Connor's stories go on for quite a long time, so we've got the storyline with Imogen, which will play out for a lot of series eight. The storyline with Connor and Christine will play out for a while as well. Along with episode four, episode ten is a big one to watch out for…"
> Read our spoiler for the next episode of 'Waterloo Road'
> Read more 'Waterloo Road' spoilers and news
Waterloo Road continues on Thursday (September 13) at 8pm on BBC One.