Six familiar Welsh faces have volunteered to put their voices on the air – and Christmas gifts on eBay - in aid of three charities, Wales Air Ambulance, NSPCC and Macmillan Cancer Care.
They are: footballer Malcolm Allen and author Catrin Dafydd; presenter Mari Lovgreen and actor Richard Elis; comedy writer Myfanwy Alexander and ex rugby player Rhodri Gomer Davies.
It's all for the S4C series Carolau Gobaith which starts on Wednesday, 5 December 8.25pm.
Without any previous experience of singing in public, they will have to perform in the concert and record a CD – which will be available to buy and download from iTunes - but there's a lot of hard work to do before then.
Responsible for preparing the stars are the Three Welsh Tenors – Rhys Meirion, Aled Hall and Alun Rhys-Jenkins - who will share their experience and expertise and all in aid of charity.
In addition, each of the stars, the Three Tenors and presenter Shân Cothi have donated a special item to sell on eBay.
They include: a chance to join the Three Tenors in the studio as they record their new CD; a Scarlets shirt signed by the team; a football training session with Malcolm Allen; and a Karen Millen coat worn by the character Davina in the award-winning series Con Passionate.
Also: a piece of literature written especially for you by author Catrin Dafydd, and a collection of her novels; a little black dress from Coast; a Gwaith/Cartref cast hoodie; and three garden gnomes in the guise of the Three Tenors, and signed by them.
To claim a unique Christmas gift, place your bid on the eBay website between Thursday 6 December and Sunday 16 December. The highest bid on 16 December wins the item with all money donated to the three charities.
There's more information about the auction on the S4C website – s4c.co.uk/carolaugobaith. There you can also follow a link to the Just Giving sites where you can sponsor the stars' efforts at any time.