The actor, who plays Andrew Robinson, confirmed that the plot involves a shock accident which his character is blamed for.
Smith told All About Soap: "I have got my biggest storyline ever coming up, which is very exciting. It's all top secret, so the only thing I can really say is that something happens which will change Andrew completely.
"There's a freak accident, which Andrew is responsible for, and he gets ostracised and the pressure of it will really get to him. He'll go from being a kid who thinks he can do whatever he likes to someone very different indeed."
Neighbours fans recently saw Andrew split from Summer Hoyland (Jordy Lucas) after more than a year together.
Discussing Andrew's romantic future, Smith added: "I can see him ending up with a party girl who isn't very smart or good at conversation, just because he'll look for someone totally different from Summer.
"I'd love to see him get together with Vanessa, but I have to admit that might be for my own personal reasons rather then Andrew's!"
Neighbours airs weekdays at 1.45pm and 5.30pm on Channel 5 in the UK, and weekdays at 6.30pm on Eleven in Australia.
Watch Digital Spy's recent interview with Jordan Smith in the video below: