“Small Things Like These” is a slim book by an Irish writer, Claire Keegan, that tells the terrifying and true story of the abuses of the Magdalene laundries over centuries in the Emerald Isle. Now, “Small Things” is a movie. It is a meditation on suffering hiding in plain sight and an explanation of what must be ignored for life to keep calm and carry on. The evil at the edge of vision is what can make a mess of bright happiness.