The Relic Novel review

The science :

Since this a techno thriller here is the science.
There is very unique plant deep in the Amazon rain forest.
This plant is infected with a fungus and this fungus is in turn
infected with a virus.The Virus is a reovirus (mentioned in the book)
and a simple google states that a reovirus infects plants and animals.
This virus modifies the cells of the plants(viruses can change the DNA).
The Virus causes an influx of animal proteins in the leaves of the plants.
Proteins are the building blocks of animal tissue (wikipedia).
(Fiction...)

Now anyone who eats these leaves will end up transforming into
the Monstrous Mbwun a terrifying beast 14 feet long and endowed
with powerful abilities.One changes into the monster after eating
the leaves of this plant as  we release animal proteins into the body.
This chimera mixture of various animals including human, needs
the leaves of those plants to survive.If the leaves of those plants are
unavailable than the Beast kills Humans to get at the Human hypothalamus
which contains what is in the leaves.The hypothalamus produces many
of the bodies essential hormones.(...fictional )

Anyway the Kothoga tribe known as "the shadow people" use this technique
to create a monster to use on there enemies .Simply feed someone the leaves of
this ancient primordial plant and transform him into the Beast , once the
Beast is large enough the Tribe goes into hiding and since the beast cannot
find the leaves it goes for the next best thing , the Human Hypothalamus.
The Monster than would hunt down neighbouring Tribes.

In the Novel the Beast wrecks havoc in a Museum in New York.