The inventor of the transporter, Emory Erickson, beams on board, because they're going to do some sort of test with the ship.
Trip takes to T'Pol, who is reading the Kir'shara. I thought they had to translate that. Erickson says he's working on a long-range sub-quantum transporter so people can beam direct from Earth to Vulcan and so on.
Erickson and Trip work on the transporter, while Erickson natters on about the early transporter work. He insists on installing a convertor or something. Meanwhile, Archer shows Erickson's daughter Danica around engineering, and suggests she might join Star Fleet.
Erickson and his daughter seem to be up to something (dun dun duuuuuun!).
Something attacks and kills a crewman in the armory. Danica and Erickson beleive they're responsible, but, of course, don't tell anyone because they're up to something (dun dun duuuuuuuuun!).
They start doing the whole transporter test thingee and beam a probe 30,000kms and it starts sending back data, which Erickson is keen to examine alone. Meanwhile, Trip tells Archer he thinks Erickson is up to somethnig (dun dun duuuuuuuun!). Archer says the anomoly which killed the crewman was also recorded on Erickson's ship a couple of years back.
The anomoly appears on the ship again, and Archer and co go looking with some MACOs. It hits T'Pol's hand, but doesn't do any lasting damage. The visual recording shows that the anomoly is soemthing humanoid - it's Erickson's son, quinn. Erickson admits the tests he's doing are to bring back his son who was lost in a test of the sub-quantum transporter prototype (which is, apparently, impossible to get working). Archer's disappointed that Erickson didn't trust him enough to tell the truth, but agrees to help.
Trip and T'Pol are skeptical, but ARcher insists they must make an attempt to rescue the lost crewman. $5 says he turns up inside out.
Trip tells T'Pol she should get out more. Quinn appears again in the shuttlebay and makes something go boom, almost killing Archer and Erickson. Trip complains to Archer again about the whole thing and thinks they should leave. Archer tells him to STFU and do his job. It's someone's time of month, by the looks.
The attempt to extract Quinn does not go well, and Quinn arrives with severe cellular damage and dies shortly after.
Enterprise heads home, and Archer and Erickson commserate. Meanwhile, Phlox clears T'Pol of Vulcan AIDS, and says that it's being cured all over Vulcan, then she talks with Trip some about what she's going though. Erickson and Danica beam over to another ship bound for Earth. Teh end.