Ithaka O. 
Moonlight Through the Manhole [EPUB ebook] 
a long short story

A first impression: you get one chance to make it…
…if you really are the first one to make contact.
Billy Clifford, a first-grade student at Everton Elementary, knows where the missing children are: under the manhole. Who put them there? The aliens, of course. So, on the night Billy sees a glimmer from under the manhole, he climbs down the sewers well prepared…