A Starfleet medical transport carrying rare bio-mimetic gel that went missing in the Hekaras Corridor in 2370 and was later trapped beside a newly formed subspace rift.
The USS Fleming is a Starfleet medical transport. In the episode Force of Nature, set in 2370, it disappears while passing through the Hekaras Corridor, the only safe route through a region of intense tetryon fields, with a cargo of valuable bio-mimetic gel.
The Enterprise searches the corridor and learns that Hekaran scientists have been disabling ships to draw attention to their theory that warp fields are damaging subspace. The Fleming turns out to be one of their victims.
When the scientist Serova deliberately breaches her own warp core to prove the point, a rift opens with the Fleming at its edge. The Enterprise coasts in without warp power and beams the crew out.