Kings met their second successive Division One team in this competition and again found the going tough as Buckingham held them for well over an hour with a well-organized performance.
The hosts had pace up front and an industrious midfield that allowed little time on the ball.
A blatant foul in the home penalty area was ignored by the referee and a tug just outside the away box on the dangerous Matt Cruse received similar treatment, but in truth, those were the only incidents of note in the first hour.
By this time, the Langley management duo had seen enough and sent on the big guns, in the form of Nick Jackson and Mitchell Weiss.
The latter made one of the most dramatic and immediate impacts that the club has ever witnessed, making the deadlock-breaking goal and then hitting a superb seven minute hat trick – all within 14 minutes of entering the fray.
Seemingly having weighed up tactics from the bench, he at once took on the defence with pace, power and control down the middle and the effect was like a fox entering a chicken coop.
His first telling contribution though was from wide left, delivering a low cross for Alex Campana to pick his spot off the far post.
Almost straight from the kick-off, the roles were reversed as a quickly taken Campana free-kick put Weiss through to beat Andy Hammond with a low shot on the run.
Four minutes later an instinctive volleyed pass by Dean Hitchcock fell to the feet of Weiss and, although Hammond partially blocked his shot, the power took it over the line.
Cue a further three minutes and Sam Warrell put an exquisite high through ball into the path of the striker and his hat-trick was complete.
A black spot was a bad injury to the versatile Connor Toomey who turned his ankle on an unpredictable pitch and will be sorely missed while out.
However, the night belonged to Weiss and Kings are one step from the final and still on course for an historic double.