As Tachia revealed on Twitter, Bolton will be making an appearance in episode 16 (due to air on Thursday, February 7) - but why is he back?
While we don't want to give too much away just yet, we can reveal that Bolton arrives at the school's new Scottish home in his army uniform as he pays a visit to Tom Clarkson.
When Nikki Boston praises Bolton as a great role model to the kids, Lorraine Donnegan decides that he should give an inspirational speech to the sixth form students.
The speech doesn't go well, partly because a cynical Grantly Budgen is riling the former pupil, but that's not the only problem as Bolton is obviously anxious and on edge.
Bolton tries to confide in Tom about what's bothering him but is interrupted, and later there's further trouble for everyone…
Waterloo Road airs on Thursdays at 8pm on BBC One.