For those who’ve seen the episode already, please spoil the minimum that’s necessary, if anything, to understand the presence of Captain Jack. We’ve just started getting Torchwood here in the US. The first two episodes have aired.
The ep will air in about 12 hours, so no spoilers about the ep itself yet please.
Captain Jack in this episode is post Torchwood Series 1. This episode explains how he got back to the 20th Century after the events of Doctor Who Series 1 – I don’t believe it spoils any of Torchwood that you haven’t already seen.
I was just thinking about this the other day and getting irritated with BBCA for choosing now to start airing Torchwood, because that really does tie in with what you’re going to see coming up in Utopia. My advice would be - if you’re real invested in following Torchwood, DVR these last 3 eps of Doctor Who and watch them after TW’s ended.