When your stuck and the light fails you need to push your film to the limit. This shot is HP5 rated at 3200 ISO and pushed using temperature rather than time. Best to use a combination of both, temperature only tends to punch out the grain but the effect can be nice. Film is pretty robust and can be abused to a point, black and white is good for this because it can be done at home, labs if they have the capability tend to charge a heap for it.
This shot was done on a Leica M7 and has held its sharpness well, important to capture the best quality picture as pushing film effects the detail you get in highlights and shadows.