Lack made no mistake from the spot.
Through two minutes and 38 seconds of stoppage time, Thistle threw everything into a desperate attempt to come back from a goal down for the fourth time in the match, but Taradale were having none of it.
On the balance of chances created, Taradale had the edge, but Thistle showed commendable spirit to stay in the fight.
Taradale goalkeeper Graham Healey was called on in the 20th minute to make a smart save of Sam Royston’s near-post glancing header from David Salmon’s right-wing cross.
Six minutes later, Taradale went ahead when Cam Patterson met a low cross from the right with an unstoppable first-time strike from 10 metres.
It could easily have been 2-0 three minutes later when Thistle keeper Mitchell Stewart-Hill had to make two good saves in quick succession. A minute later, Healey followed suit with a near-post save of Somerton’s hard, low shot from an acute angle on the left. A fine parry by Stewart-Hill in the 36th kept Thistle in touch, and in the 39th they equalised.
Right-winger Campbell Hall crossed, left-winger Royston challenged for the high ball and Somerton picked up the pieces, blasting the ball high into the net from close range.
Former Thistle player Brandon Josling gave Taradale a second-half lead in the 53rd minute. Matt Smith, playing double centreback with Finn McAuley, had fouled a Taradale player just outside the penalty area. Josling hit the resulting free-kick low and hard past the open side of the wall, towards the far post. It was past Stewart-Hill before he could move.
Three minutes later, Stewart-Hill again kept the Jags in with a shout, coming out to block a shot near the edge of the penalty area.
In the 63rd, Elwood varied his short-passing game with a long ball to Somerton, who scrapped to keep hold of it until he was close enough for the 15-metre angular drive into the far corner that brought Thistle level at 2-2.
In the 79th minute, Taradale went ahead again after a series of defensive missteps left Lack receiving the ball in the clear going into the penalty area from the old inside-left position. As Jags defenders closed in, he deftly placed the ball past the advancing keeper.
Thistle looked to have salvaged a point in the 86th when Alex Shanks, who had come on for Hall four minutes earlier, gave a short ball to Somerton. He feinted to the right, went left instead and let fly with a 20-metre left-footer that gave Healey no chance as it flew into the bottom right-hand corner.
Then came the 90th-minute drama that decided the match.
For a first competitive outing in four weeks, Thistle did well. The passing and first touch looked a little rusty, but the fitness held up. The demands of competitive play will refine the performance in coming weeks.
Elwood had a solid, if unspectacular, Federation League debut. He roamed the midfield, offering options, linking play and, when the opportunity arose, hitting a pass that could make a difference. Beside him, McMillan was the perfect foil, hustling, bustling and making a nuisance of himself as Taradale tried to build play. In front of them, Salmon worked hard trying to set up the frontrunners, but it was his delivery from wide out that took the eye.
Thistle’s standout players were at either end of the pitch. The efforts of keeper and skipper Stewart-Hill and striker Somerton kept the Jags in with a chance right to the end.
Royston gave a wholehearted performance on the left flank, and Hall was a handful when he had the opportunity to run at his marker.
The defence had a mix of experience and youthful vigour. Rightback Daniel Venema is a wily campaigner who gives of his best, McAuley is a committed stopper who will benefit from the experience of those around him, Smith has an aerial game that adds to his qualities of composure and football nous, and leftback Baple has the speed and tenacity of a terrier.
They’re not the finished product, but they offer plenty to work with, and coach Garrett Blair has other players to add to the mix.
On Saturday, Thistle play Napier City Rovers Reserves in Napier in the fifth of their eight league games away. The postponed match against Palmerston North United will be played on September 2.