Thor #256 (1977)

"Lurker in the Dark!"  Cover pencils by John Buscema, inks by Frank Giacoia, script by Len Wein, pencils by John Buscema, inks by Tony Dezuniga.  The Asgardians come across a monstrous derelict starship and decide to investigate. Inside, they are attacked by Securitrons, but after a thorough thrashing and a lucky shot at Sif, they are called off by Relstor. After they disappear, Sif collapses.  Back in Asgard, after the nurses have cared for Sif and left, Sporr's tentacles carry her off. Thor and the Asgardians, unable to  stop it, swear to find her and destroy her captor.

Very good condition.