Images from the box of Betrayal at Calth show us the full contents of the box. This is what is in there, including only 1 Contemptor. Its fully listed with a total of 38 miniatures. There are lots of close up pics of the sprues here.
This Box Contains
48 page rule boook
4 double sided board tiles
42 reference, command
and damage cards
Assorted card counters and 12 dice
38 Citadel Miniatures
Captain Aethon
Kurtha Sedd
Sor Gharax, Contemptor Dreadnought
30 Tactical Space Marines
5 Legion Terminators
You can see the leaked images and a whole host close up pics. It seems the images going around are from Spikey Bits.
http://www.spikeybits.com/2015/10/new-pics-horus-heresy-contemptor-in-plastic.html
http://www.spikeybits.com/2015/10/breaking-unseen-horus-heresy-box-set-pics.html
http://www.spikeybits.com/2015/10/breaking-new-contemptor-cataphractii-pictures.html
http://www.spikeybits.com/2015/10/breaking-new-mark-iv-astartes-pictures.html