A valleys house had a problem that left even the experts scratching their heads and the new owner with difficulties in getting to sleep such was the worry - no wonder it initially went to auction.
But it's not as though this house was hiding its horror- the damp was plain to see for Homes Under The Hammer presenter and experienced property professional Martin Roberts to spot straight away.
This three-bed terrace in Ebbw Vale clearly had a major problem and it was a puzzle for Martin.
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Wallpaper was sliding down the walls, plaster was crumbling away and the damp had invited its friend mould into the kitchen, which was sinisterly creeping around in a room too gross to now even contemplate cooking in.
But why? It was mainly on the interior walls on both sides that joined the neighbouring terraces, so was it coming up, coming down or coming through?
Martin thought it might be to do with the chimney breast and the roof's lead flashing but one thing he was sure about when he saw more damp on the opposite wall.
"The running theme with the walls in this house seems to be problems!' he exclaimed.
The kitchen in a single-storey extension at the rear was riddled with damp with Martin shocked to see it was just about everywhere - ceilings, floors, walls. His resounding option was it needed some money spending on it and it was "YUK!"
The issues in the kitchen could probably be blamed on the fact it was housed within a rundown extension, but what about the damp inside the main section of the house?
Martin was the first confused visitor; there were to be more.
The house went to auction with a guide price of £32,000 and was bought by experience developer David for £45,500.
He had appeared on the show with his previous renovation in Pontypridd and had actually renovated many properties during his career.
So the damp issues did not worry him; yet.
With a budget of £18,000 and a timescale of four months decided, Martin wandered off still mulling over the damp while David got stuck into transforming this Valleys three-bed terrace into the latest addition to his rental portfolio.
And so it began - 'David Versus Damp' - let the battle commence.
And it was a long battle as the programme did not return for another 18 months and it is still unclear who the outright winner of this epic HUTH house battle is.
On first inspection, the upgrade of this home is full and fancy.
New windows, new rendering, new electrics and plumbing and plastering were tackled throughout.
Add a new bathroom, swanky new kitchen, and French doors to the garden too and these were easy warm-up bouts on this renovation fight card, leading up the main event.
The roof, although not replaced, had to be repaired and included a whole new ridge as water was leaking down the chimney breast.
Damp issue solved then, the fight is over with a knockout punch by David in the first round? Nope.
The persistent damp was not done, it got up and jumped back in the ring for another round.
David says: "The house did fight back on this one! We had to damp course twice because it came back again, my builder had sleepless nights on this and so did I!
"The damp was quite a problem because I had four different experts come to the property to inspect and they all actually gave me four independent, different opinions.
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"So we tried the first one and that didn't work and the second one we consulted some more people and it was a real issue and we've had one or two re-emergences so we've got to still do a tiny bit more damp course in places."
David explains the extent of the confusion here, with even the experts foxed by this house.
David says: "The amount of head scratching the professionals have been doing here, they've said 'it has really challenged us' and it's challenged me too."
Maybe the fight should be called a draw then. But where David definitely did win was with the figures.
Even though the reoccurring damp issues cost him more than he hoped and eaten into his profit, he surely has been rewarded for all his effort and loss of sleep?
The spend on the renovation project David says was £19,000 and the estate agent who revisited was impressed by the standard of finish at the house, especially the plastering, bathroom, kitchen and flooring.
The agent's valuation of £90,000 would give David and his partner Louise a pre-tax and fees profit of £25,500 on their £64,500 total spend.
But the plan is for a long term rental at this house that has been a puzzle for so many people, but no confusion on what David would make - just over a 12% yield based on a £650 per calendar month rent.
So David is the clear winner here on points but, who knows, maybe one day the damp will reappear to demand a rematch.
This story is in series 24, episode 58, currently available to watch on BBC iPlayer.
