The O.D.S.T fireteam Epsilon is betrayed by their spartan in command,

The reason for this is largely unknown, but it is suspected that his own fireteam was hiding a flood spore as a last ditch effort to keep the spartan in-line, who had a history of falling out of line of course. 445 has and always will be difficult to trust under certain circumstances but the UNSC knows better than to send him to oversee an ordinary squad that couldn't fight against him. As it turns out, even the best of the best may not be enough to save them from vengance.