After two long years in the void, Will is glad to be home, and so is his family. However he still has his job to do: Feliogustus has favors to pay back after being without Will for so long and some of those favors are coming due. So while having his homecoming interrupted isn't enjoyable, paying back those gods that Feliogustus owes is important.
When an opportunity to take on a task on one of the core worlds as a favor to another god comes along, Will must drop everything and deal with it immediately. Will's never been to a core world before, much less heard of them, but to Feliogustus it's important that he goes because invites to the core are few and far between. So while the task may seem to be mundane to Will, he knows from experience that there's more going on than Feliogustus has told him. And anything that's important to Fel, is important to Will.
When Will gets there he finds that some of the 'rules' that the gods play by are different in the core, as well as some of the rules that govern the infinite and the portals that link it all together. Will finds that instead of one realm, the place he's now in is made up of multiple realms linked together by portals that not only most people can see, but which are in fact big enough to sail both trading vessels and warships through.
