John Sheridan came back to the Proact to haunt his former side, though thanks to the Millers, Spireites increasingly faint play-off hopes remain alive.
Two Argyle teenagers put the visitors two up in the opening half hour as Chesterfield strung together their worst 45 minutes of the season at a time when heroes were needed.
Spireites were given a lifeline before the hour mark through an own goal and they dominated the second half, but were largely toothless against a side who were desperate for points at the opposite end of the table.
Joe Bryan converted his first even league goal in some style.
Plymouth had been on top, Conor Houlihane and Reuben Reid had both threatened, but they went one better when the teenager, borrowed from Bristol City, received on the left of the box.
With everyone expecting a cross, he curled in a right-footer beyond Tommy Lee and the ball nestled in at the far post.
The goal failed to shock Spireites into determined action and within five minutes, Argyle had doubled their lead.
Marc Richards failed to control from a harmless free-kick into the box and his error was compounded when 19 year old Curtis Nelson pounced to hit the ball into the roof of the net from close range.
Manager Paul Cook pushed Drew Talbot up front in a desperate bid to get his side to start playing, but Plymouth continued to look the most likely to add to the goals tally.
Mark Randall’s angled free-kick forced Jake Cole to punch away and Jay O’Shea had a shot blocked in a couple of rare first half raids for the flimsy Spireites.
Liam Cooper headed high from a corner soon after the restart but he then made a dreadful back-pass and Lee had to be sharp to narrow the angle for Bryan to hit his gift wide.
Chesterfield made a double substitution and it paid off immediately.
Teenager Alex Henshall delivered a cross from the left and, standing at the far post all alone, Guy Branston erred and knocked the ball into his own net.
Left-sider Henshall was at the centre of most of Spireites’ more positive moves, delivering teasing crosses and corners though Argentinian midfielder Andres Gurrieri had a great chance to wraps things up seven minutes from time when he shot wide with a one on one after referee Nigel Miller had blocked a clearance for the potential assist.