-- talk to him again to find out where he thinks he's going.
He's heading for Boston, and he has no intention of stopping before he gets there. But as you recall from the letter that gave you this case, he tries this every night and never makes it; the boat is found floating in the middle of the Hudson River every morning.
There is a way to trick him into thinking he's finally reached Boston. Did you notice that if you ask him how far you are from Boston, he doesn't look out the window? Instead, he checks the GPS screen. Maybe we can muck with the GPS somehow.
In previous games, it was established that when Joey gets near electronic things that rely on airborne signals, like radios and cell phones, they get messed up. Try that here.
As Joey, stand next to the GPS so it beeps and boops. As Rosa, ask Ryan how far you are from Boston.
You'll have to do this repeatedly because the GPS is literally all over the map. Eventually, it settles on Boston, and Ryan is happy as a clam.
For a little bit, and then he remembers where he is. Now is the time for Joey to use his other ghostly ability, the tie.