As Riley prepares to marry Mercedes McQueen, Doug is aware that the wannabe WAG cheated on the naïve footballer with her future father-in-law Carl.
Although Doug wants to reveal all, dangerous Warren Fox has warned him to keep his nose out as he's keen to keep his own vicious blackmail scheme on track. However, with the clock ticking down and Riley about to exchange his vows with Mercedes, will Doug crack and expose the truth at the ceremony?
Here, actor PJ Brennan - who plays Doug - chats to Digital Spy about the wedding episode.
Have you enjoyed being part of the big wedding storyline?
"Definitely. I didn't realise early on that it would be such a big storyline for the year, but it's grown and grown over time and now it's going to be a big moment for the show.
"To be a part of it has been absolutely fantastic, especially getting to work with different cast members like Jamie Lomas, who plays Warren. Doug often ends up in scenes with the bad boys, and it was nice to get a bit more screen time with Jamie."
What's going through Doug's mind as the wedding approaches?
"I think it's very complicated because Doug doesn't want to be the one to say anything to Riley. That's partly because of the threats coming from Warren, but also because Seth knows and Doug thinks that the news would be better coming from Riley's own brother.
"Also, I think Doug is very separate from the truth of the matter. He knows the secret, but only by chance, while Seth knows all of the people and circumstances involved. That adds to Doug's belief that Seth should be the one to tell the truth, because he's the one with first-hand information about it."
"Well, as it gets closer and closer to the moment, I think Doug realises that it's do or die, and it might just have to be him that is the bearer of bad news. As much as Doug doesn't want to be that person, he might have to be. Doug values his friendship with Riley far too much to just stand by and do nothing."
How worried is Doug about Warren's threats?
"Very worried! Doug isn't aware of the fact that Warren is a killer, but because of the stuff that happened in the late-night episodes, he definitely believes Warren when he's threatening to break his legs - or to go even further! It's definitely not just an empty threat. Doug realises that Warren is a dangerous person who could kill him over this, so the threats feel very real.
"I tried to bear that in mind when I was playing the scenes, because it made it feel a lot more dramatic. The big question is whether Doug's friendship with Riley is strong enough to overpower those threats…"
"Definitely. I think that ever since that turning point happened where Doug let go of the past that he had, he's been constantly aware of keeping on the straight and narrow. Ever since his return, that's what Doug has been focused on.
"Doug's had a few missteps, but something like his friendship with Riley is so important for him. There's no part of it that's based on dirty dealings or anything like that, and it's a friendship that's very important for Doug to maintain. I do think that Doug's actions are always influenced by the fact that, at one point, he was a person who hurt other people and didn't make the best choices."
Due to this storyline, you've been working a lot with Miles Higson (Seth) for the first time. Have you enjoyed getting some screen time with him?
"Yes - Miles is one of my best friends on the show, so it's been nice to work with him a bit more. I think the Doug and Seth friendship has been really nice to explore, too. The two characters seem to blend very well together.
"It's nice to see Seth's character take a turn as well - he's delving a little bit deeper into the more sinister side of things. I think Seth is a great character. He's one of the more normal characters on the show, so I think he's someone that the audience can empathise with. I think Doug is too, so it's quite a nice pairing."
What was it like to film the dark and sinister wedding advert that we've seen on Channel 4 and E4 recently?
"It was great! I mean, I'm only in it for about 0.2 seconds and I wasn't there for the whole day, but it was great. I was excited to be part of it. I remember watching last year's Fire Week promo on TV and thinking that I would love to be part of something like that. So when I found out that I was going to be involved in this promo, I was absolutely ecstatic.
"I think it turned out really, really well. I've just been home briefly back to Brooklyn, and I made my parents watch it about four times, because I love it! And if I was an audience member, that would have definitely got me interested in tuning in, so I think it did everything it needed to do and a bit more."
After such a big build-up, is the wedding going to be worth the wait for viewers?
"Oh yeah, it's a perfect, perfect wedding for a soap opera. All of the players come together and gather at the right moment, and the tension rises perfectly. We've seen a great build-up recently, but in the wedding episode itself, I do think the audience will absolutely love what happens.
"It's quite unexpected as well - there are a few surprises! The viewers are going to love it and I honestly think it's all been worth the wait."
Hollyoaks' wedding episode airs tonight at 7pm on E4 and Monday at 6.30pm on Channel 4.
> Read our interview with Rob Norbury, who plays Riley, about the wedding
> Hollyoaks' Rachel Shenton teases Mitzeee, Costello revenge plot
> Hollyoaks Mercedes, Riley wedding promo shot released - First Look
> Hollyoaks wedding: More pictures from Mercedes and Riley's big day
> Hollyoaks wedding has huge repercussions, says Jennifer Metcalfe
> Read more Hollyoaks spoilers and news