"The story, such as it is, is that Snape was working in his lab and a spell backfired in some new and painful way, but of course, Mrs Malfoy will get the whole story." As much as Sebastian likes Narcissa, she's only slightly more/less terrifying than Moody and he knows that when talking to her he can't lie or prevaricate even slightly.

"And, yes, we should call him."