[05/23/2019 @ 1:45 PM] Fare was removed by airline. Expired. If it goes back online we will put up a post about it.
Delta has round-trip flights from Houston (HOU/IAH) to Dusseldorf or Frankfurt (DUS/FRA) for $502-$533 with a connection. Flights June to July. Departures on Tuesday, Wednesday, and Thursday. 7-day minimum stay required.
Note: Carry-on bag is allowed for free on Delta. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.