Rebuilding Ukraine after the destruction inflicted by Russia will be a gigantic task. Foreign donors have pledged billions of dollars. But they want reassurances that the money will be properly spent, in a country which still has high levels of corruption. For Assignment Tim Whewell visits Bucha, near the capital Kyiv, site of some of the worst Russian atrocities, to see the beginning of reconstruction. A series of shocking reports by Ukrainian journalists into alleged misuse of rebuilding funds have forced local authorities in the area to explain themselves. But a new state reconstruction agency committed to transparency has now also started work in Bucha. And anti-corruption campaigners believe a new digital accounting and monitoring system they are developing in collaboration with the authorities will help turn Ukraine into a world beacon of openness. The government's slogan is "build back better." But what exactly does that mean? And can it be achieved?