Fergal and Georgie are stunned to find Zak in their home in Sunday's Fair City on RTÉ One and the RTÉ Player.
It's all part of the feud between Fergal and Zak's father Tommy, which centres on a dodgy box that Tommy bought from Fergal.
In a bid to keep the peace, Georgie invites Zak for coffee, but while ordering, Zak steals his house keys.
Later, as Fergal and Georgie talk in the house, Zak appears.
"Welcome home, lads," he says. "Just wondering what more I should do to get that apology for me da?"
"What do you think, Georgie?" asks Zak as he dangles Georgie's house keys in front of him.
Fans can watch what happens next on Sunday on RTÉ One and the RTÉ Player at 8:30pm.
Fair City airs on RTÉ One and the RTÉ Player on Sundays, Tuesdays, Thursdays, and Fridays.
