Lethal Promise led her rivals a merry dance in the Ballyhane Blenheim Stakes at Fairyhouse.
Following successive runner-up finishes at the Curragh in May, Willie McCreery's filly opened her account in impressive fashion at Naas in June.
She again performed creditably when fourth in the Group Three Grangecon Stud Stakes on her next start, but disappointed when favourite for a Listed contest at Newbury on her latest outing.
Racing back on home soil, Lethal Promise was an 8/1 shot under Billy Lee and soon grabbed the lead and dictated affairs from there on in.
The challengers tried to bridge the gap in the home straight, but McCreery's charge never looked in real danger of being caught and passed the post a length and three-quarters ahead of 2-1 favourite Inverleigh.
Mia Mento put up an improved performance to grab third.
McCreery said: "I think we were just riding her wrong the last twice. We were trying to hold her up and make her get home and I think we cheesed her off a little bit.
"It's great for the team. There are quite a few of them here today enjoying the day and it's a beautiful evening.
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"She's a good filly going forward and that'll be it for the year now, we'll finish with her for the season and let her grow into herself."
