Derbyshire 304 (Masood 91, Dal 52) and 255 for 5 (Masood 62, Madsen 54) drew with Middlesex 401 (Eskinazi 118, de Caires 80, White 65, Thomson 4-103) and 258 for 5 declared (Holden 82, White 81)
Helm struck three times in 19 balls to give Middlesex the upper hand after half-centuries by Shan Masood and Wayne Madsen had threatened to secure Derbyshire’s first Lord’s success in 20 years.
Pursuing a target of 356 from 88 overs, Derbyshire reached 197 for 2 just after tea – but Helm’s fiery spell forced them to abandon hopes of victory.
Richard Johnson, Middlesex’s returning head coach, said: “That’s the Tom Helm I knew a long time ago when he came through and hopefully we’ll see him really push on. What I saw today was international-class bowling.
“He hit great areas, swung it – it was quality all the way through. If he does that week in, week out, England have to come calling for him because he’s up there with the best on that.”
The home side extended their second innings by just six overs in the morning, with not-out batters Robbie White and Max Holden both falling to Sam Conners in pursuit of quick runs.
Another 57 were added, largely thanks to some clean striking by John Simpson and Toby Roland-Jones before Murtagh waved them in at 258 for 5.
However, Murtagh himself was soon back in the pavilion after pulling up in the ninth over and Masood settled into the groove, dominating his partnership of 81 with Billy Godleman as Middlesex searched in vain for a breakthrough.
That finally arrived in the third over after lunch as Ethan Bamber – having already beaten the bat several times – persuaded Masood to flick on the leg side and Simpson took a diving catch.
Godleman briefly took up the baton with a couple of boundaries off Bamber, but the skipper then attempted to cut the first ball of Roland-Jones’ second spell and was caught in the slips for 38.
After a slow start, Madsen began to go for his shots, employing the reverse sweep to good effect against spinner Josh de Caires and reaching his half-century just after tea with a crisp straight drive for four off Roland-Jones.
But Helm raised Middlesex’s hopes with a trio of wickets, including those of Madsen who was leg before and Brooke Guest , smartly taken by Stephen Eskinazi at first slip after the pair had shared a stand of 91.
That left Derbyshire to survive 27 more overs and – although Dal got away with a loose shot that narrowly eluded Helm at deep square leg – handshakes were exchanged with five of those still unbowled.