Huw Edwards investigates the case of the disappearing house near Llandeilo. WWII defences at Holyhead and searches for a lost castle at Portmeirion.

Huw Edwards and his team interpret the strange humps and bumps in the Welsh uplands (Pen-blaen-Milo). A model farm (Leighton Park Farm) and a medieval wall painting (Ciliau).

This time, Huw Edwards and his team examine a Tudor house (Old Impton Farm), a Roman theatre (Tomen-y-Mur) and a chapel (Llanelli).

Huw Edwards and his team decipher the writing on a stone pillar (Eliseg's Pillar), recreate what an iron age fort (Gaer-Fawr) would have looked like and uncover an 18th century copper works (Swansea).

Huw Edwards and the history detectives discover a lost church (Tal-y-Cafn), search for the oldest castle (Hay-on-Wye) gate in Europe and find out how the great engineer Thomas Telford built the highest aqueduct (Pont Cysyllte) in the UK.