The most aggressive of ocean predators, the bull shark, is notorious for leaving the safety of the deep blue ocean, venturing far up the murky rivers of Africa's coast in search of prey. But lurking in these shadowy places is Africa's deadliest killer – the Nile crocodile. Reports of clashes between the two are many, but marine researchers Ryan Johnson and Tess Hempson are determined to find out the truth.

The most aggressive of ocean predators, the bull shark, is notorious for leaving the safety of the deep blue ocean, venturing far up the murky rivers of Africa's coast in search of prey. But lurking in these shadowy places is Africa's deadliest killer – the Nile crocodile. Reports of clashes between the two are many, but marine researchers Ryan Johnson and Tess Hempson are determined to find out the truth.