"The reason I’m here with such urgency is I’ve just heard rumour – strong rumour – that the Ministry seized an illegal Time-Turner from Theodore Nott and has kept it. For investigation. Let me use that Time-Turner. Let me have my son back."
-- Amos Diggory to Harry (CC1.6)
The Experimental Time-Turner is a time-turner prototype built of cheap metal that would allow the user to transport himself back in time for five minutes (CC2.7. CC3.7, CC4.4).
- Had a different appearance than the hourglass-shaped Ministry Time-Turners, and was discovered by Aurors in the possession of Theodore Nott, a classmate of Draco’s and son of one of Voldemort’s Death Eaters (CC1.5).
- Stolen from Hermione Granger’s Minister for Magic Office by Scorpius Malfoy, Albus Potter, and Delphi (Diggory) (CC1.19).
- Used several times by Scorpius, Albus and Delphi to travel back to the Triwizard Tournament in the years 1994-95 in an attempt to save the life of Cedric Diggory, who was killed as a “spare” when the Triwizard Cup portkey took Cedric to the graveyard and Voldemort with Harry (CC2.7, CC2.20, CC3.8).
From the Web
Pottermore: Harry Potter and the Cursed Child
The theatre production opened in the West End of London at the Palace Theatre on 31 July 2016: Harry Potter and the Cursed Child, Parts One and Two