His search leads Fergus to infiltrating the underwater research operations on Enceladus, an ice-crusted water moon of Saturn, as a pilot of an underwater transport, in order to gain the access needed to find his friends. As usual, almost nothing goes to plan for Fergus - or Duncan MacInnis, as he called himself in Enceladus - and he finds himself at odds with the local bully, stuck with his predecessor's cat, and in a place that is darker than anywhere he's ever been... like space, but without the stars. He'll need to find some trustworthy friends and find some unconventional solutions if he hopes to rescue his friends... that is, assuming they're still alive. And even the Deep, itself, is a weight on him... drivers usually either quit and walk away or... it ends badly. Working in the deep, dark waters of Enceladus, trapped beneath the ice, dependent on instruments to know where anything is and dependent on others for the ability to leave proves to be more mentally stressing than anything Fergus has faced before.
Of course, after his adventures in Finder, Fergus has a "superpower" of sorts. He can generate jolts of electricity with his body. That could be a neat parlor trick and could be a great tool, but it's not so convenient as one might think, when the vessel that keeps him alive under all of that water could be accidentally fried and the ability seems to want to use itself when he's stressed or under duress. Also, when the ability is useful and he uses it frequently, the thirst it causes can be tiring and debilitating. Ah, water, water everywhere... and all that.
If you haven't read Finder, yet, I highly recommend you start there and then read Driving the Deep, as they would work best when read in chronological order, but I do believe Driving the Deep could be enjoyed on its own, if necessary. Personally, I read both, enjoyed both, and am looking forward to the further adventures of Fergus Ferguson. Highly Recommended.