Well I'm glad I didn't wear mascara to this performance, or I would have looked like a zebra by the end. But while Fourth Dog is very moving in places, it is also funny, acerbic, and wise. Zena Forster's writing is tight and surprising, and it packs a hell of a lot into about 80 minutes, with constant earthy distractions (the set features a toilet, for instance, as well as a lot of fluffy white wedding veiling).

Human Story Theatre focus on plays with a health or social care issue at their heart, and breast cancer plays an important part in Fourth Dog. But while health education may be an underlying aim, it isn't the focus - much like the title, this important theme is quite oblique, and vies with some other major strands, not least the history of female medicine, the point of marriage, trying to beat statistics, and the nature of love and marriage. It's an agenda that might be seen as particularly female-orientated, and it has meaty characters of both genders, and all ages. It's really only at the Q&A afterwards with healthcare professionals and a first-hand account of going through diagnosis and treatment for breast cancer that we see this is real motive of the piece.

The setting is a wedding reception: a heavily pregnant bride and her younger groom have just tied the knot, dressed up as novelist Fanny Burney and her husband Alexandre D'Arblay. The bride's mother has been joined by her sister, though the pair haven't been speaking, and the bride's grandmother and her husband bicker. The acting is excellent all round, but the scene is slightly stolen by Karen Ford and John Tolputt as the oldest generation. This pair get some of the best lines, and through their relationship the recognition and value of women's domestic work is explored: grandfather points out how much younger he looks than his wife "I've looked after myself over the years." "Yes, and I've looked after yourself too," she snaps back.

Fanny Burney's extraordinary account of a mastectomy (in France, in 1811, with no anaesthetic) is one climax, but again it vies with grandmother's rousing speech on love and marriage and why her husband shouldn't leave her now, and also with a hilarious (and wonderfully inappropriate) rousing George Formby number.

It's easy to assume that something educational might not be much fun. But Fourth Dog is first and foremost and excellent piece of drama. It is entertaining. The fact it makes you think, be moved, and check for lumps when you get home is just a bonus.