Nine-man Wealdstone suffered play-off heartbreak after a last-gasp 2-1 defeat at Lowestoft Town.
The Stones had seen Chris O'Leary and Sean Cronin dismissed and were sunk in the sixth minute of injury time through a Dean Sinclair penalty.
Chris Henderson fired the hosts in front midway through the first half with a close-range finish.
But Gordon Bartlett's side equalised just after the hour mark when Scott Fitzgerald headed in Lee Chappell's cross.
But a three minute spell proved costly for the visitors as they were reduced to nine men. First O'Leary received a second yellow card for shoving Scott Mitchell.
Then Sean Cronin was sent off for a two-footed challenge on Sinclair.
Wealdstone were always up against it after these setbacks and conceded a penalty deep into injury time when Lubo Guentchev was brought down by Scott McCubbin.
Sinclair stepped up and found the net to send Lowestoft through to the final and end the Stones' season in the cruellest way possible.