The Exon strain has been created in laboratory conditions but due to emergency venting of the biodome, the plants have escaped and birds have propagated them around the country.
In Wales the helicopter carrying Howard crashes, and he is found near a group of plants over 8 feet tall – far taller than any others and with correspondingly higher oxygen output.
To compensate for the missing scan Howard's helicopter array is used, and the UN ambassador is satisfied that all Exon Strain plants can be destroyed, so calls off the carpet bombing.
Flinders, collating his notes realises that the Exon strain has been leaching chemicals out of the ground, and where it has been destroyed has left a rich natural fertiliser, meaning future harvests will be greater.
The radio play states that the country will be bombed with defoliants – drawing an analogy with Operation Ranch Hand in Vietnam, however they actually plan to use herbicides instead, which kill plants rather than stripping leaves.