An Air That Kills: How long can you hold your breath?

The atmosphere in the lab is toxic.

It is only a matter of time before there is a flu pandemic with the potential to kill billions.

Or so wealthy entrepreneur Lyle Lynstrum believes. That is why he is funding research into transgenics - the mechanism by which viruses can jump the species barrier - at a high security lab on a tidal island off the North Devon coast.

A suspiciously rapid turnover of staff has him worried. He sends in scientist Katie Flanagan as an undercover lab technician. Something is clearly very wrong, but before Katie can get to the bottom of what is going on, a colleague is struck down by a mysterious illness.

Has the safety of the facility been compromised, allowing a deadly virus to escape? Katie begins to suspect that the scientists are as deadly as the diseases - and that her cover has been blown.

Then the island is cut off by high seas and a terrifying game of cat-and-mouse begins...