  With a infrared luminosity of nearly 10^13 Lsuns, IRAS 09104+4109 is the most
luminous galaxy with z<0.5 in the IRAS All Sky Survey. A radio-loud Seyfert 2
type optical spectrum, a cD host galaxy in a rich cluster, and a massive
cooling flow make IRAS 09104+4109 unique among ultraluminous infrared galaxies.
Cannibalized cluster members and the cooling intercluster medium may contribute
both the fuel and the dust needed to re-radiate the power of IRAS 09104+4109
into the far-infrared. We have imaged IRAS 09104+4109 in the WFPC2 F622W,
F814W, and FR680N filters on the HST to obtain rest frame 4300A, 5700A, and
[OIII] emission line images on sub-kpc scales. IRAS 09104+4109 displays a
complex morphology on the smallest scales, with radiating filaments, an
asymmetric [OIII] nebula, and a number of very faint, irregular blue objects
surrounding the cD galaxy. We discuss the nature and possible interplay between
the enshrouded QSO nucleus, the cD host galaxy and the irregular cluster.
